AlgebraMediumWidth of a pen fenced on three sides
Algebra practice question
A farmer builds a rectangular pen against a straight wall, so fencing is needed on only three sides: two sides of length w metres and one side of length w + 5 metres. The farmer uses exactly 41 metres of fencing. What is the value of w?
Answer: 12
w + w + (w + 5) = 41 gives 3w = 36, so w = 12.
Common wrong answers
- If you answered 9
- 9 solves 4w + 5 = 41, fencing four sides.
- If you answered 17
- 17 is the length of the third side.
- If you answered 13.67
- 13.67 divides 41 by 3, ignoring the extra 5.
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