Question

the fourth proportional of 5,8 and 15 is

Answer 1

Let the fourth proportional be x.

5:8::15:x

Product of means=Product of extremes

x=8×15/5
=24

Answer 2

Let the fourth proportional be x

We know Proportion = 5 : 8 :: 15 : x

Product of means = Product of extremes

5 * x = 8 * 15

x = 8 * 15 / 5

x = 8 * 3

x =24.

The fourth proportional of 5,8,15 is 24.