Question

12 is the mean proportional of _____________.

• A. 16 and 9
• B. 12 and 14
• C. 19 and 22
• D. 16 and 24

Answer 1

The correct option is A

16 and 9

Mean proportional (b) = $\sqrt{ac}$

Consider option A. Find mean of 16 & 9

$b=\sqrt{ac}=\sqrt{16\times 9}=\sqrt{144}=\sqrt{{12}^2}=12$

Mean of 16 & 9 = 12. Hence, the correct answer is A.

Mean proportionals of option b, c, d do not equal 12.