RRB Technician 2014 Ques 6
Question: If the mean of the following data is 13.5, then the value of p is
x 5 10 p 20 25 f 10 10 10 2 8
Options:
A) 15
B) 150
C) 10
D) None of these
Show Answer
Answer:
Correct Answer: A
Solution:
- $ x _{i} $ $ f _{i} $ $ f _{i}\times x _{i} $ 5 10 50 10 10 100 p 10 10p 20 2 40 25 8 200 $ \Sigma f _{i}=40 $ $ \Sigma f _{i}x _{i}=10p+390 $
$ \therefore $ Mean $ (\bar{{}x})=\frac{\Sigma f _{i}x _{i}}{\Sigma f _{i}}=\frac{10p+390}{40} $
$ \Rightarrow $ $ 135=\frac{10p+390}{40} $
$ \Rightarrow $ $ 135\times 40=10p+390 $
$ \Rightarrow $ $ 540-390=10p $
$ \therefore $ $ p=\frac{150}{10}=15 $
BETA
