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JAMB Mathematics 1990 Question 31

Question 31

Mensuration of Plane Shapes

In the diagram above, the area of PQRS is 73.5cm2 and its height is 10.5cm. Find the length of PS if QR is one-third of PS.

Diagram for this question
  1. A.21cm
  2. B.17½cm
  3. C.14cm
  4. D.10½cm
Show the answer and explanation

Answer: D (10½cm)

Explanation

Let PS = x, so QR = x/3. Area = ½(x + x/3) × 10.5 = 7x = 73.5, so x = 10.5cm.