Question

The mean of observations x, x+3, x+5, x+7 and x+10 is 9. What will be the mean of last three observations

Answer 1

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

5x+25=45

5x=45-25

5x=20

x=4

mean of last three observations = x+10+x+7+x+5/3

= 4+10+4+7+4+5/3

=12+22/3=34/3=11.33 approx

Answer 2

Answer:

11.33

Step-by-step explanation:

$\text{According to the question,}\\\\\dfrac{x+x+3+x+5+x+7+x+10}{5} = 9\\\\\\\implies \dfrac{5x + 25}{5} = 9\\\\\\\implies \dfrac{5(x+5)}{5} = 9\\\\\\\implies x+5 = 9\\\\\\\implies x = 9-5\\\\\implies x = \boxed{4}\\\\\\\text{Last three observations are x+5 = 4+5 = 9, x+7 = 4+7 = 11, and x+10 = 4+10 = 14}\\\\\text{Mean of last three observations = } \dfrac{9+11+14}{3}\\\\\\= \dfrac{34}{3}\\\\\\= \large \underline{\boxed{\boxed{\bold{11.33}}}}$

Hope it helps!