16Hit1600
AlgebraMediumRange of a side from a perimeter limit and an area minimum

Algebra practice question

A square must have a perimeter of at most 60 centimetres and an area of at least 100 square centimetres. Which inequality describes all possible side lengths s, in centimetres?

  1. A. 10 ≤ s ≤ 15Correct
  2. B. 10 < s < 15
  3. C. s ≤ 15
  4. D. 100 ≤ s ≤ 60

Answer: A. 10 ≤ s ≤ 15

4s ≤ 60 gives s ≤ 15, and s² ≥ 100 gives s ≥ 10: 10 ≤ s ≤ 15.

Why the other answers are wrong

B. 10 < s < 15
Both limits are inclusive.
C. s ≤ 15
Omits the area condition.
D. 100 ≤ s ≤ 60
Those are the limits on perimeter and area, not on s.

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