Problem 3 · 2016 Math Kangaroo
Medium
Algebra & Patterns
substitution
Ruth takes part in the kangaroo competition where 30 questions have to be answered. She answers every question and each answer is either right or wrong. She has 50% more right than wrong answers. How many of her answers are right?
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Answer: D — 18
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Hint 1 of 2
Let the number of wrong answers be one part.
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Hint 2 of 2
Right is 1.5 parts; right + wrong is 30.
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Approach: parts model
- If wrong = 2 parts then right = 3 parts (50% more).
- Total 5 parts = 30, so 1 part = 6.
- Right answers = 3 parts = 18.
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