RRB Technician 2014 Ques 5
Question: If the mean of five observations x, $ x+2,x+4,x+6,x+8 $ is 11, then the mean of first three observations is
Options:
A) 9
B) 11
C) 13
D) None of these
Show Answer
Answer:
Correct Answer: A
Solution:
- Here sum of 5 observations $ =x+(x+2)+(x+4)+(x+6)+(x+8)=5x+20 $
$ \therefore $ Mean of total observations $ =\frac{5x+20}{5}=11 $
$ \Rightarrow $ $ 5x+20=55 $
$ \therefore $ $ x=7 $
$ \therefore $ Mean of first three observations $ =\frac{7+9+11}{3}=\frac{27}{3}=9 $
BETA
