Question

the diameter of a spherical ball is 21 cm how much leather is required to prepare 5 such balls

Answer 1

Radius of ball=21/2
Total surface area of sphere=4pie r^2
=4×22/7×21/2×21/2=1386cm^2
Now,Total surface area of 5 balls
=5×1386=6930cm^2
So,6930cm leather is required

Answer 2

Tsa of sphere = 4πr^2
= 4×22/7×10.5×10.5
= 9702/7
=1386cm^2
Total leather req. = 1386×5
=6930