Question

The mean and standard deviation of $10$ observations are $35$ and $2$ respectively. Find the changed mean and standard deviation if each observation is increased by $4$.

• A. $39$ & $6$
• B. $2$ & $39$
• C. $39$ & $2$
• D. $6$ & $39$

Answer 1

Answer: (C)

$39$ & $2$

When each observation is increased by $4$, the mean of the changed observations will also increase and it will become equal to $35+4=39$.
Since increment in all observations by a constant does not change the standard deviation. Thus, the mean and standard deviation when each observation is increased by $4$ would be $39$ and $2$ respectively.