Question

how many spheres of 15 cm diameter can be covered by 10mxm of material

Answer 1

area to be covered = n*4 pi R square
                               = n*4 * 22/7 * .075 * .075 
                               = n*.0707 m*m
area of the material = 10m*m
no of spheres which can be covered = 10m*m/.0707
                                                          ~ 141

Answer 2

we know that TSA of sphere is 4πr²
area of cloth= 10m²=10×100²=100000cm²
Tsa of sphere=4πr²
                     =4×22/7×225
                     =2827.4cm²
total no.of spheres=100000/2827.4
                             =35.3
∴35 spheres can be covered