Question

Q.15 Find the mean proportional of 81 and
121.​

Answer 1

81 : x :: x : 121

product of outer term=product of means term

$981 \times 121 = x^{2} \\ {x}^{2} = 9801$

$x = \sqrt{9801} \\ x = \sqrt{99 \times 99}$

$x = 99$

check your answer

81 : 99 :: 99 : 121

81× 121=99×99

9801=9801