Question

if the mean of five observations x , x+2,x+4,x+6,x+8 is 13 find the value of x and hence find the mean of the last three observation

Answer 1

Mean = Sum of all observations / Number of observations

=> 13 = ( x + x + 2 + x + 4 + x + 6 + x + 8) / 5

=> 65 = 5x + 20

=> 5x = 45

=> x = 9

Now,

Mean of last three = ( x + 4 + x + 6 +x + 8) /3

= ( 9 + 4 + 9 + 6 + 9 + 8) /3

= ( 27 + 18)/3

= 45/3

= 15

Answer 2

Hope it helps ,

Thanks.