The radius of base of solid cylinder is 7 cm and its height is 21 cm. It is melted and converted into small bullets. Each bullet is of same size. Each bullet consisted of two parts viz. a cylinder and a hemisphere on one of its base. The total height of bullet is 3.5 cm and radius of base is 2.1 cm. Approximately how many complete bullets can be obtained ?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 ie 83.
Volume of solid cylinder = πr²h = (22/7) × (72) × 21
= 22 × 7 × 21 = 3234
Volume of 1 bullet = πr²1h + (2/3)π r³1
= πr²1 [h + (2/3) × r1]
= (22/7) × (2.1)² [1.4 + (2/3) × 2.1]
= 22 × 0.3 × 2.1 (1.4 + 1.4)
= 22 × 0.3 × 2.1 × 2.8
= 38.808
No. of bullets = 3234/38.80 = 83.33 ≈ 83