Question

The mean of $21$ observations (all different) is $40.$ If each observations greater than the median are increased by $21,$ then mean of observations will become

• A. $50$
• B. $50.5$
• C. $30$
• D. $45$

Answer 1

Answer: (A)

$50$

Mean $=40$

Sum $40\times 21=840$

Median term $=\frac{21+1}{2}={11}^{th}term$

Number of terms $=21-11=10$

sum of the increased 1 term $=21$

sum of the increased 10 term $=21\times 10=210$

sum of the 21 observation after the increase $=840+210=1050$

Mean of the 21 observation $=\frac{1050}{21}=50$