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WAEC Mathematics 1995 Question 29

Question 29

Mensuration of Solids

The diagram above shows a cone with the dimensions of its frustrum indicated. Calculate the height of the cone.

Diagram for this question
  1. A.12cm
  2. B.15cm
  3. C.18cm
  4. D.24cm
  5. E.30cm.
Show the answer and explanation

Answer: D (24cm)

Explanation

The small cone cut off is similar to the whole cone. With height H: (H − 12)/H = 6/12, so 2H − 24 = H and H = 24 cm.