Question

Mean of $11$ observations is $17.5$. If one observation value $15$ is deleted, then the mean of remaining observations is ___________.

• A. $15.75$
• B. $16.75$
• C. $17.75$
• D. $18.75$

Answer 1

Answer: (C)

$17.75$

Sum of the observation $=11\times 17.5=192.5$

If one observation value $15$ is deleted then new sum of observations will be:

$192.5-15=177.5$
And the number of observations will decrease by $1$ i.e. $10$.

New mean $=\frac{177.5}{10}=17.75$