JEE Main 12 Jan 2019 Morning Question 20
Question: If the sum of the deviations of 50 observations from 30 is 50, then the mean of these observations is [JEE Main Online Paper Held On 12-Jan-2019 Morning]
Options:
A) 30
B) 51
C) 31
D) 50
Show Answer
Answer:
Correct Answer: C
Solution:
- Here, $ \sum\limits _{i=1}^{50}{(x _{i}-30)=50} $
$ \Rightarrow \sum\limits _{i=1}^{50}{x _{i}=50+50\times 30} $
$ \therefore $ Mean $ =\frac{\sum\limits _{i=1}^{50}{x _{i}}}{50}=\frac{50\times 31}{50}=31 $
