Question

the mean of observationx,x+3,x+5,x+7andx+10 is 9,then find the mean of last three observations

Answer 1

(x+x+3+x+5+x+7+x+10)/5=10
then (5x+25)/5=10
5x=25
x=5
so mean of last three= (x+5+x+7+x+10)/3
=(3x+22)/3
put value of x=5
37/3 is the mean

Answer 2

Hii..

here is ur answer :-

Observation = x, x+3 , x+5, x+7, x+10

Given,

Mean = 9

Mean = sum of all observation / Number of observation

9 = x + x +3 + x + 5 + x + 7 + x + 10/ 5

9 = 5x + 25/5

5x +25/5 =9

5x+25= 9*5

5x +25 = 45

5x = 45-25

5x = 20

x = 20/5

x = 4

So, value of last three observation :--

x+5 = 4 + 5 = 9

x + 7 = 4 +7 = 11

x + 10 = 4 + 10 = 14

Mean of the last three number :--

= 9 + 11 + 14/ 3

= 34 /3

= 11.33

Hope it helps u!!