Question

When $10$ is subtracted from all the observations, the mean is reduced to $60\%$ of its value. If $5$ is added to all the observations, then the mean will be

• A. $25$
• B. $30$
• C. $60$
• D. $65$

Answer 1

The correct option is B $30$

If $10$ is subtracted from all the observations then mean will reduce by $10$.
New mean $=60\%$ of the original mean
Let mean $=$$M$
$\Rightarrow M-10=0.6M$
$\Rightarrow M=25$
If $5$ is added to all the observations, new mean will be $25+5=30$.