Question

if the mean of the observations x,x+3,x+5,x+7,x+10 is 9 , find the last observation.

Answer 1

here mean = 9= (x+x+3+x+5+x+7+x+10)/5
so 5x+20 =45
5x= 25
x= 5
last observation was x+10 so it would be equal to 5+10 = 15