16Hit1600
Problem-Solving and Data AnalysisEasy–MediumBalls of wool for a longer scarf

Problem-Solving and Data Analysis practice question

A knitting pattern uses 3 balls of wool for a scarf 120 centimetres long. At the same rate, how many balls of wool are needed for a scarf 200 centimetres long?

Answer: 5

3/120 = 1/40 ball per centimetre, so 200 cm needs 200/40 = 5 balls.

Common wrong answers

If you answered 4
4 rounds the answer down for no reason.
If you answered 6
6 doubles 3 as though 200 were twice 120.
If you answered 80
80 is the extra length in centimetres.

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