Question

If 150 is the third proportional to 6 and x; find the value of x.

• A. 30
• B. 60
• C. 63
• D. 34

Answer 1

The correct option is A 30

If a : b :: b : c, then we say that a, b, c are in continued proportion, and
c is the third proportional of a and b.
Here, $b^2=ac$
Given the third proportional of $6,x$ is 150

$=>x^2=6\times 150=6\times 6\times 25$

$=>x=\sqrt{6\times 6\times 25}$

$x=6\times 5=30$