Find the fourth proportional to the numbers 100 : 50 : 30

Find the fourth proportional to the numbers 100 : 50 : 30

A 30

B 15

C 25

D Cannot be determined

E None of these

Solution

Correct Answer: Option B

Let the fourth number be a.

Then, 100 : 50 : : 30 : a

i.e., 100 x a = 30 x 50

⇒ a = 3 x 5

⇒ a = 15