Question

If the mean proportion of 3 and $a$ is 6. Find $a$

• A. 144
• B. 48
• C. 2
• D. 36

Answer 1

The correct option is D

36

Since 6 is the mean proportion of 3 and $a$

we have 3 : 6 :: 6 : $a$

$\frac{3}{6}=\frac{6}{a}$

$3a$ = 36

$a$ = 12