Question

find the no of solid sphere each of diameter 6cm that can be made by melting a solid metal cylinder of height 4.5 cm and diameter 4cm

Answer 1

Okay! Now, we know that by melting and recasting, the volume will remain constant or same.

So, the volume of sphere divided by volume of cylinder will amount to the number of spheres made.

While doing the division, cut the pi's. Then, it would look like this:-

4*3*3/4*4.5
= 4*9/4*4.5

As 4 is common in both the numerator and denominator and we are multiplying in both numerator and denominator, we can cut out 4 as well. Then, 

9/4.5 = No. of spheres made
         = 2