SSC CHSL 2024 PYQ — Question 60

SSC CHSL - 08 July 2024 - Shift 1 • Quantitative Aptitude • Q60

A solid sphere of radius 8 cm is melted and then recast into small spherical balls each of diameter 4 cm. Find the number of balls thus obtained (use π=227π={22\over7}).

Show answer & explanation

Correct answer: B

Explanation

The correct answer is option 2 i.e. 64.

Short Trick:

The total number of small spherical balls = R3/r3 = 8323\frac{8^3}{2^3} = 64

Alternate method:

The volume of a sphere = (4/3)πr3, where r is the radius.

The radius of the large sphere (R) = 8 cm

Volume of the large sphere = (4/3)π(83) = (4/3)π(512) = (2048/3)π cm3

The diameter of each small sphere = 4 cm

So, the radius of each small sphere (r) = 2 cm

Volume of each small sphere = (4/3)π(23) = (4/3)π(8) = (32/3)π cm3

Number of small spheres = (2048/3)π(32/3)π\frac{(2048/3)\pi}{(32/3)\pi} = 64

Therefore, 64 small spherical balls can be obtained.