the average of 'n' numbers is x. when 36 is subtracted from two of the numbers, the new average becomes(x-8). the value of 'n' is

Question

find the value of 'n' 

(a) 6                  (b) 8

 

(c)  9                  (d)  72

 

(e)  None of these

 

Answer 1

the underlying formula that you want to use to solve this one is that

(x - 8) = New Sum / n

(x - 8) = (nx - 72) / n

solving that algebraically for the value of "x" yields

n(x - 8) = nx - 72

nx - 8n = nx - 72

-8n = -72

n = 9

Answer 2

Let S be sum of n numbers. Then S/n=x and (S-72)/n =x-8

 

S/n    =  x

S/n-72/n = x - 8

 

S/n-72/n+8 = S/n

 

72/n=8

 

n=72/8

x=9