Question

If the geometric mean of a and 120 is 60, find the value of a.

Answer 1

`\text{ Geometric mean of two numbers } a \text{ and } b , \text{ where } a,b>0 \text{ is given by } G= √(ab)`

`√(a\cdot120)=60`

`\implies 60 \cdot 2 \cdot a=60\cdot 60 \qquad \text{Squaring both sides}`

`\implies a =30`

Answer 2

The answer is option 4.

Explanation:

Given that the mean formula is total score/number of score. So we can assume that total score is (a+120), number of score is 2 and the mean value is 60. Then you have to find the value of a :

`(a + 120)/(2) = 60`

`a + 120 = 60 * 2`

`a + 120 = 120`

`a = 120 - 120`

`a = 0`