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data/explorations/protractor_test_1.yaml
1 034 строки
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Kevin Thomas
Introduce edits_allowed property (#15396)
04 май 2022, 01:14
Не верифицирован
04 май 2022, 01:14
0d3d9c6
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author_notes: '' auto_tts_enabled: true blurb: '' category: Mathematics correctness_feedback_enabled: false edits_allowed: true init_state_name: Intro language_code: en objective: learn how to count permutations accurately and systematically param_changes: [] param_specs: guess: obj_type: UnicodeString schema_version: 47 states: END: classifier_model_id: null content: content_id: content html: <p>Congratulations, you have finished!</p> interaction: answer_groups: [] confirmed_unclassified_answers: [] customization_args: recommendedExplorationIds: value: [] default_outcome: null hints: [] id: EndExploration solution: null next_content_id_index: 0 param_changes: [] recorded_voiceovers: voiceovers_mapping: content: {} solicit_answer_details: false written_translations: translations_mapping: content: {} Final challenge: classifier_model_id: null content: content_id: content html: '<p>Now here''s a final challenge: using what you''ve learned, can you figure out how many ways there are to arrange four balls in a row? Listing all the possibilities by hand is going to be tedious, but, by now, you''ve learned at least one way to calculate this number quickly and accurately.</p>' interaction: answer_groups: - outcome: dest: END feedback: content_id: feedback_1 html: '<p>Yes, that is correct: the answer is 4 times the number of ways to arrange three balls in a row, so it is 4 times 6, which is 24! Well done.</p>' labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: 24.0 rule_type: Equals tagged_skill_misconception_id: null training_data: [] - outcome: dest: Final challenge feedback: content_id: feedback_2 html: <p>Ahem. That, I think, is a trick answer, surely? I am pretty sure there's at least one way to arrange four balls in a line...</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: 0.0 rule_type: IsLessThanOrEqualTo tagged_skill_misconception_id: null training_data: [] - outcome: dest: Final challenge feedback: content_id: feedback_3 html: '<p>Hmm, that''s close-ish, but not quite. It feels like you may not have found all the possible cases. It''s really quite easy to miss some of them. You''re close to solving this, though. There''s an easy way and a hard way. The easy way is to use the reasoning we''ve developed previously to calculate the answer with a single multiplication. The hard way is to systematically find all the cases, and make sure that you haven''t missed any. It''s up to you whichever you pick, but you need to get an accurate answer!</p>' labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: a: 18.0 b: 23.0 rule_type: IsInclusivelyBetween tagged_skill_misconception_id: null training_data: [] - outcome: dest: Final challenge feedback: content_id: feedback_4 html: '<p>I think you''ve overcounted. This is quite common in counting problems, especially if you aren''t working systematically, or aren''t explicitly listing the things you''re counting. If you''re working from a list of possibilities, check it to make sure you have no duplicates! And you might also consider using the approach we''ve developed earlier in the exploration -- it''s much easier, and less prone to errors.</p>' labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: 24.0 rule_type: IsGreaterThan tagged_skill_misconception_id: null training_data: [] confirmed_unclassified_answers: [] customization_args: {} default_outcome: dest: Final challenge feedback: content_id: default_outcome html: <p>Hmm, I don't think so, there are quite a lot more than that. Check your work, and try again.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null hints: [] id: NumericInput solution: null next_content_id_index: 5 param_changes: [] recorded_voiceovers: voiceovers_mapping: content: {} default_outcome: {} feedback_1: {} feedback_2: {} feedback_3: {} feedback_4: {} solicit_answer_details: false written_translations: translations_mapping: content: {} default_outcome: {} feedback_1: {} feedback_2: {} feedback_3: {} feedback_4: {} Found all the ways: classifier_model_id: null content: content_id: content html: <p>So, you've found that there are six ways to arrange these three balls.<br><br>Is that the same as your first guess?</p> interaction: answer_groups: - outcome: dest: Introspection feedback: content_id: feedback_1 html: <p>Was it? I think you guessed {{guess}}, but there were actually 6 ways.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: 0 rule_type: Equals tagged_skill_misconception_id: null training_data: [] - outcome: dest: Introspection feedback: content_id: feedback_2 html: <p>Yes, you thought the number of ways was {{guess}}, but it was actually 6.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: 1 rule_type: Equals tagged_skill_misconception_id: null training_data: [] confirmed_unclassified_answers: [] customization_args: choices: value: - content_id: ca_choices_3 html: <p>Yes</p> - content_id: ca_choices_4 html: <p>No</p> showChoicesInShuffledOrder: value: false default_outcome: dest: Introspection feedback: content_id: default_outcome html: '' labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null hints: [] id: MultipleChoiceInput solution: null next_content_id_index: 5 param_changes: [] recorded_voiceovers: voiceovers_mapping: ca_choices_3: {} ca_choices_4: {} content: {} default_outcome: {} feedback_1: {} feedback_2: {} solicit_answer_details: false written_translations: translations_mapping: ca_choices_3: {} ca_choices_4: {} content: {} default_outcome: {} feedback_1: {} feedback_2: {} General Theory: classifier_model_id: null content: content_id: content html: "<p>So: <br><br>There is 1 way to arrange 1 ball.<br>There are 2 ways\ \ to arrange 2 balls.<br>There are\xC2\_6 ways to arrange 3 balls.<br><br>Let's\ \ give these names. We will say F1 = 1, F2 = 2, F3 = 6. So, if you have n\ \ balls (where n is 1, 2, 3, ...), then Fn is the number of ways to arrange\ \ them.<br><br>Can you see a pattern here, or a systematic way to count them?\ \ Let's have a look at the 3-ball case.<br><br>--------------------------------------------------------------------------------------------<br><br>First\ \ you pick the ball on the left. This could be red, blue or yellow. There\ \ are three cases to consider:<br><br>If the first ball is red, then there\ \ are two balls left to arrange in the other two slots. And there are F2 ways\ \ to do this.<br>If the first ball is blue, then there are two balls left\ \ to ... hey, this is the same thing, it's just F2.<br>And, if the first ball\ \ is yellow, then ... yada, yada, F2.<br><br>So the total number of ways to\ \ arrange 3 balls, F3, is equal to 3 * F2. And all this works out correctly,\ \ because F2 = 2, and F3 = 3 * 2 = 6.<br><br>--------------------------------------------------------------------------------------------<br><br>Now,\ \ can you write out a similar expression for F2, in terms of F1? Then we'll\ \ move on to figuring out F4, which starts to become hard to compute manually.</p>" interaction: answer_groups: - outcome: dest: Final challenge feedback: content_id: feedback_1 html: <p>Yes! F2 = 2 * F1, since there are two ways to pick the ball on the left, and for each of these 2 ways, there are F1 ways to arrange the other balls.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_7 normalizedStrSet: - 2F1 rule_type: Contains tagged_skill_misconception_id: null training_data: [] - outcome: dest: Final challenge feedback: content_id: feedback_2 html: <p>Yes! F2 = 2 * F1, since there are two ways to pick the ball on the left, and for each of these 2 ways, there are F1 ways to arrange the other balls.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_8 normalizedStrSet: - 2*F1 rule_type: Contains tagged_skill_misconception_id: null training_data: [] - outcome: dest: Final challenge feedback: content_id: feedback_3 html: <p>Yes! F2 = 2 * F1, since there are two ways to pick the ball on the left, and for each of these 2 ways, there are F1 ways to arrange the other balls.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_9 normalizedStrSet: - F1*2 rule_type: Contains tagged_skill_misconception_id: null training_data: [] - outcome: dest: Final challenge feedback: content_id: feedback_4 html: <p>Yes! F2 = 2 * F1, since there are two ways to pick the ball on the left, and for each of these 2 ways, there are F1 ways to arrange the other balls.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_10 normalizedStrSet: - 2 * F1 rule_type: Contains tagged_skill_misconception_id: null training_data: [] - outcome: dest: Final challenge feedback: content_id: feedback_5 html: <p>Yes! F2 = 2 * F1, since there are two ways to pick the ball on the left, and for each of these 2 ways, there are F1 ways to arrange the other balls.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_11 normalizedStrSet: - F1 * 2 rule_type: Contains tagged_skill_misconception_id: null training_data: [] confirmed_unclassified_answers: [] customization_args: placeholder: value: content_id: ca_placeholder_6 unicode_str: Type your answer here. rows: value: 1 default_outcome: dest: Final challenge feedback: content_id: default_outcome html: <p>Alas, I don't understand the answer you just typed. Was it something like F2 = 2 * F1? If so, you are correct! There are two ways to pick the first ball, and F1 ways to pick the second one. This all works out because F1 = 1, so F2 = 2 * 1 = 2.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null hints: [] id: TextInput solution: null next_content_id_index: 12 param_changes: [] recorded_voiceovers: voiceovers_mapping: ca_placeholder_6: {} content: {} default_outcome: {} feedback_1: {} feedback_2: {} feedback_3: {} feedback_4: {} feedback_5: {} rule_input_10: {} rule_input_11: {} rule_input_7: {} rule_input_8: {} rule_input_9: {} solicit_answer_details: false written_translations: translations_mapping: ca_placeholder_6: {} content: {} default_outcome: {} feedback_1: {} feedback_2: {} feedback_3: {} feedback_4: {} feedback_5: {} rule_input_10: {} rule_input_11: {} rule_input_7: {} rule_input_8: {} rule_input_9: {} Guess a generalization: classifier_model_id: null content: content_id: content html: '<p>Now, let''s think about what happens if we had different numbers of balls. We know that the answer for three balls is 6. What if we had four balls to arrange?<br><br>Here''s a possible idea: 3 times 2 is 6, so the answer for four balls must be 4 times 2, which is 8. Basically, we just multiply the number of balls by 2, and get the answer. We''ve already shown that it works for 3 balls; we can figure out exactly why later.<br><br>Do you believe this reasoning? Do you agree that there are exactly 8 ways to arrange four balls of different colours in a line?</p>' interaction: answer_groups: - outcome: dest: Two balls feedback: content_id: feedback_1 html: <p>All right! We have an answer. We could check it, I guess, by listing all sequences of four balls. But let's do something easier; let's try it with just two.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: 0 rule_type: Equals tagged_skill_misconception_id: null training_data: [] confirmed_unclassified_answers: [] customization_args: choices: value: - content_id: ca_choices_2 html: <p>Yes! It's clearly 8.</p> - content_id: ca_choices_3 html: <p>No, I don't think it's 8.</p> showChoicesInShuffledOrder: value: false default_outcome: dest: Two balls feedback: content_id: default_outcome html: '' labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null hints: [] id: MultipleChoiceInput solution: null next_content_id_index: 4 param_changes: [] recorded_voiceovers: voiceovers_mapping: ca_choices_2: {} ca_choices_3: {} content: {} default_outcome: {} feedback_1: {} solicit_answer_details: false written_translations: translations_mapping: ca_choices_2: {} ca_choices_3: {} content: {} default_outcome: {} feedback_1: {} Intro: classifier_model_id: null content: content_id: content html: '<p>Suppose you were given three balls: one red, one blue, and one yellow. How many ways are there to arrange them in a straight line?</p>' interaction: answer_groups: - outcome: dest: correct but why feedback: content_id: feedback_1 html: '' labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: 6.0 rule_type: Equals tagged_skill_misconception_id: null training_data: [] - outcome: dest: Intro feedback: content_id: feedback_2 html: <p>Surely there's at least one? For example, you might have the red ball on the left, the blue ball in the middle, and the yellow ball on the right. Now try and find a few more. How many different ways can you find, in total?</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: 0.0 rule_type: IsLessThanOrEqualTo tagged_skill_misconception_id: null training_data: [] confirmed_unclassified_answers: [] customization_args: {} default_outcome: dest: Not 6 feedback: content_id: default_outcome html: '' labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null hints: [] id: NumericInput solution: null next_content_id_index: 3 param_changes: [] recorded_voiceovers: voiceovers_mapping: content: {} default_outcome: {} feedback_1: {} feedback_2: {} solicit_answer_details: false written_translations: translations_mapping: content: {} default_outcome: {} feedback_1: {} feedback_2: {} Introspection: classifier_model_id: null content: content_id: content html: "<p>Can you think a little bit about why your answer was different from\ \ six? Did you count a particular arrangement twice, or did you miss one?<br><br>Making\ \ sure that you've counted everything can be tricky! Two common mistakes are\ \ counting one thing twice, and forgetting to count some of the things. These\ \ can be overcome by counting systematically and doing sanity checks.<br><br>In\ \ the next few explorations, we'll explore what it means to count systematically,\ \ and we'll talk a little about sanity checks. But why don't you try and discover\ \ some of these for yourself? Take\xC2\_a couple of minutes, and think a bit\ \ about some checks you can make to ensure that you don't overcount or undercount\ \ things, or a systematic way that you could have used to count the balls.\ \ Write these down here -- you will probably want to refer to them in a future\ \ exercise, and we'll show your jottings to you again at that point.</p>" interaction: answer_groups: - outcome: dest: Introspection feedback: content_id: feedback_1 html: <p>Come on, surely you have something...</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_3 normalizedStrSet: - '' rule_type: Equals tagged_skill_misconception_id: null training_data: [] confirmed_unclassified_answers: [] customization_args: placeholder: value: content_id: ca_placeholder_2 unicode_str: Type your answer here. rows: value: 1 default_outcome: dest: Guess a generalization feedback: content_id: default_outcome html: '' labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null hints: [] id: TextInput solution: null next_content_id_index: 4 param_changes: [] recorded_voiceovers: voiceovers_mapping: ca_placeholder_2: {} content: {} default_outcome: {} feedback_1: {} rule_input_3: {} solicit_answer_details: false written_translations: translations_mapping: ca_placeholder_2: {} content: {} default_outcome: {} feedback_1: {} rule_input_3: {} Not 6: classifier_model_id: null content: content_id: content html: "<p>OK, you found {{guess}} ways to do this. I'd be interested in seeing\ \ what you came up with; could you list the different ways?\_Write them as\ \ three-character words, like this:<br><br>\_ \_ \_RBY<br><br>This means:\ \ put the red ball on the left, the blue ball in the middle, and the yellow\ \ ball on the right. Can you list all the ways you found?<br><br>\_ \_\_</p>" interaction: answer_groups: - outcome: dest: Not 6 feedback: content_id: feedback_1 html: <p>At least one of your list elements seems to be wrong. Can you check and make sure that each of them is a three-letter uppercase string that contains only the letters 'B', 'R' and 'Y' once each?</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_7 unicodeStrSet: - RYB - BRY - BYR - RBY - YRB - YBR rule_type: HasElementsNotIn tagged_skill_misconception_id: null training_data: [] - outcome: dest: Not 6 feedback: content_id: feedback_2 html: <p>You seem to have missed some arrangements with the red ball on the left...</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_8 unicodeStrSet: - RBY - RYB rule_type: OmitsElementsIn tagged_skill_misconception_id: null training_data: [] - outcome: dest: Not 6 feedback: content_id: feedback_3 html: <p>I think you're missing some!</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_9 unicodeStrSet: - YBR - YRB rule_type: OmitsElementsIn tagged_skill_misconception_id: null training_data: [] - outcome: dest: Not 6 feedback: content_id: feedback_4 html: <p>Have you found all the arrangements with a blue ball on the left?</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_10 unicodeStrSet: - BRY - BYR rule_type: OmitsElementsIn tagged_skill_misconception_id: null training_data: [] - outcome: dest: Found all the ways feedback: content_id: feedback_5 html: '' labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_11 unicodeStrSet: - <p>RYB</p> - <p>BRY</p> - <p>BYR</p> - <p>RBY</p> - <p>YRB</p> - <p>YBR</p> rule_type: Equals tagged_skill_misconception_id: null training_data: [] confirmed_unclassified_answers: [] customization_args: buttonText: value: content_id: ca_buttonText_6 unicode_str: Add item default_outcome: dest: Not 6 feedback: content_id: default_outcome html: <p>No, try again.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null hints: [] id: SetInput solution: null next_content_id_index: 12 param_changes: - customization_args: parse_with_jinja: true value: '{{answer}}' generator_id: Copier name: guess recorded_voiceovers: voiceovers_mapping: ca_buttonText_6: {} content: {} default_outcome: {} feedback_1: {} feedback_2: {} feedback_3: {} feedback_4: {} feedback_5: {} rule_input_10: {} rule_input_11: {} rule_input_7: {} rule_input_8: {} rule_input_9: {} solicit_answer_details: false written_translations: translations_mapping: ca_buttonText_6: {} content: {} default_outcome: {} feedback_1: {} feedback_2: {} feedback_3: {} feedback_4: {} feedback_5: {} rule_input_10: {} rule_input_11: {} rule_input_7: {} rule_input_8: {} rule_input_9: {} Two balls: classifier_model_id: null content: content_id: content html: <p>Let's try to find (or validate) a general pattern by looking at small cases. We do this because it's easy to compute the answers for small cases by hand, and they give us data which we can use to try and figure out a more general pattern.<br><br>The most obvious small case is 1 ball! There's one way to arrange one ball in a line.<br><br>How about 2 balls? How many ways are there to arrange two balls, with different colours, in a line?</p> interaction: answer_groups: - outcome: dest: General Theory feedback: content_id: feedback_1 html: <p>Yes! That is correct. If the balls are red and blue, either the red one comes first, or the blue one comes first. Once you've picked the first one, the other choice is fixed.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: 2.0 rule_type: Equals tagged_skill_misconception_id: null training_data: [] - outcome: dest: Two balls feedback: content_id: feedback_2 html: '<p>Hm. Might you be thinking that, since the answer for 3 balls is 6, the answer for 2 balls must be 4, because you just multiply by 2? If so, alas, you''ve fallen into a trap! Look carefully at the 1-ball case: the answer is not 1 x 2 = 2, it is just 1. So this ''multiply by 2'' idea is not correct. We should be careful to avoid drawing conclusions based on just a single case. Why not try again? How many ways are there to arrange two balls in a row?</p>' labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: 4.0 rule_type: Equals tagged_skill_misconception_id: null training_data: [] - outcome: dest: Two balls feedback: content_id: feedback_3 html: <p>Nah, that can't be right :-) There's at least one way to arrange two balls in a row, isn't there?</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: 0.0 rule_type: IsLessThanOrEqualTo tagged_skill_misconception_id: null training_data: [] - outcome: dest: Two balls feedback: content_id: feedback_4 html: <p>There's at least one more way. Try swapping the balls?</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: 1.0 rule_type: Equals tagged_skill_misconception_id: null training_data: [] confirmed_unclassified_answers: [] customization_args: {} default_outcome: dest: Two balls feedback: content_id: default_outcome html: <p>I think you may have counted something too many times. Try to remember the systematic approach you came up with earlier, and use it here...</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null hints: [] id: NumericInput solution: null next_content_id_index: 5 param_changes: [] recorded_voiceovers: voiceovers_mapping: content: {} default_outcome: {} feedback_1: {} feedback_2: {} feedback_3: {} feedback_4: {} solicit_answer_details: false written_translations: translations_mapping: content: {} default_outcome: {} feedback_1: {} feedback_2: {} feedback_3: {} feedback_4: {} correct but why: classifier_model_id: null content: content_id: content html: <p>Right! Why do you think it is 6?</p> interaction: answer_groups: - outcome: dest: END feedback: content_id: feedback_1 html: <p>Yes, the question is asking for the number of permutations of 3 different balls, and that is 3! = 3 x 2 x 1. You can think about this by noticing that there are 3 ways to pick the first ball -- then, once you've done that, there are 2 ways to pick the second, and the last choice is forced. That's 3 x 2 = 6 ways.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_4 normalizedStrSet: - permutation rule_type: Contains tagged_skill_misconception_id: null training_data: [] - outcome: dest: END feedback: content_id: feedback_2 html: <p>Yes, the question is asking for the number of permutations of 3 different balls, and that is 3 factorial, or 3 x 2 x 1. You can think about this by noticing that there are 3 ways to pick the first ball -- then, once you've done that, there are 2 ways to pick the second, and the last choice is forced. That's 3 x 2 = 6 ways.</p> labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null rule_specs: - inputs: x: contentId: rule_input_5 normalizedStrSet: - factorial rule_type: Contains tagged_skill_misconception_id: null training_data: [] confirmed_unclassified_answers: [] customization_args: placeholder: value: content_id: ca_placeholder_3 unicode_str: Type your answer here. rows: value: 5 default_outcome: dest: correct but why feedback: content_id: default_outcome html: '<p>OK! There are indeed 6 ways to arrange the balls: there are 3 ways to choose the leftmost one, and for each of these, there are 2 ways to choose the second one; the last choice is then forced. This gives 3 x 2 = 6 scenarios. If you do a quick search for the words ''permutation'' or ''factorial'' on the Internet, you''ll also be able to find more information about this topic. See if you can figure out what the answer for 4 balls is!</p>' labelled_as_correct: false missing_prerequisite_skill_id: null param_changes: [] refresher_exploration_id: null hints: [] id: TextInput solution: null next_content_id_index: 6 param_changes: [] recorded_voiceovers: voiceovers_mapping: ca_placeholder_3: {} content: {} default_outcome: {} feedback_1: {} feedback_2: {} rule_input_4: {} rule_input_5: {} solicit_answer_details: false written_translations: translations_mapping: ca_placeholder_3: {} content: {} default_outcome: {} feedback_1: {} feedback_2: {} rule_input_4: {} rule_input_5: {} states_schema_version: 42 tags: [] title: Protractor Test