Question

The mean of six numbers is $20$. If one number is excluded, the mean is $15$. Then the value of the excluded number is:

• A. $40$
• B. $42$
• C. $45$
• D. $48$

Answer 1

The correct option is C $45$

The mean of $6$ number $=20$.

The sum of $6$ number $=6\times 20=120$.

If one number is excluded,

Then mean of $5$ number $=15$.

And, sum of $5$ number $=5\times 15=75$.

$\therefore$ The excluded number is $=120-75=45$.

Hence, option $C$ is correct.