JAMB Mathematics 1978 Question 33

Question 33

Mensuration of Solids

A hollow right prism of equilateral triangular base of side 4cm is filled with water up to a certain height. If a sphere of radius 1/2cm is immersed in the water then the rise of water is

  1. A.1cm
  2. B.√3π/24 cm
  3. C.π/(24√3) cm
  4. D.24π/√3 cm
  5. E.24√3 πcm
Show the answer and explanation

Answer: C (π/(24√3) cm)

Explanation

The sphere's volume is (4/3)π(½)³ = π/6. The base area is (√3/4) × 16 = 4√3, so the rise is (π/6) ÷ 4√3 = π/(24√3)cm.