Question

If the mean proportional of 18 and 98 is 2A + 6, the value of A is:

• A. 16
• B. 19
• C. 18
• D. 17

Answer 1

Answer:

C. 18

Mean proportional = geometric mean.

So,
$\sqrt{18 \times 98}$

$18 \times 98 = 1764$

$\sqrt{1764} = 42$

Given:

$2A + 6 = 42$
$2A = 36$
$\Rightarrow A = 18$