One number is three times of the other and their arithmetic mean is 10 find them

x = 10, y = 20/6

Given

one number is three times of the other

their arithmetic mean is 10

Required

The numbers

Solution

Suppose the numbers you are looking for are x and y, then :

x = 3y (equation 1)

The arithmetic mean : the average of values

(x+3y)/2=10

x+3y = 20 (equation 2)

Substitute equation 1 into equation 2

3y+3y=20

6y=20

y = 20/6

from equation 1 :

x= 3 x 20/6

x = 60/6

x = 10

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