Multiply the volume by 3. For example, suppose the volume of the sphere is 100 cubic units. Multiplying that amount by 3 equals 300.
Divide this figure by 4π. In this example, dividing 300 by 4π gives a quotient of 23.873.
Calculate the cube root of that number. For this example, the cube root of 23.873 equals 2.879. The radius is 2.879 units.
25% 0ut of 27 should be 6.75, as let's say 27 =100%
So to get 25% we have to divide 100 by 25, to which the answer =4.
Same we have to do to 27- divide it by 4 to get the answer.
I hope it's right.