Question

3number are in the ratio 2:5:7 .sum of their squares is 720 .what is the average of the 3 numbers?

Answer 1

2K
5K
7K

(2K)² +(5K)² + (7K)²
4K²+25K²+49K²=720
78K²=720
K²=720/78=9.230769231
K=3.038218101
NUMBERS=6.076436202,15.191090505 ,21.267526707
SUM=42.535053414
AVERAGE=14.178351138(SUM/TOTAL NUMBER)

Answer 2

let the no.'s be 2x,5x and 7x
4x²+25x²+49x²=720
78x²=720
x²=9.23076923077
x=3.03821810125
hence the numbers are
  6.0764362025,15.1910905062,21.2675267088
so,the avg=22.2802660758