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

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by mahalababu

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by mahalababu

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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)

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