The average of 11 results is 50. If the average of the first six results is 49 and that of the last six is 52, the sixth number is.

A. 48 B. 50 C. 52 D. 56 Answer: Option D

Solution(By Apex Team)

$\begin{array}{l}\text{Mean of 11 results =50}\\ \text{⇒ Sum of these 11 results =550}\\ \text{Sum of first six results }\\ =49\times6 =294\\ \text{Sum of last six results }\\ =52\times6=312\\ \end{array}$ Sixth result = Sum of first six results + Sum of last six results − Sum of all 1 results $=294+312-550=56$

A. 20
B. 21
C. 28
D. 32

A. 18
B. 20
C. 24
D. 30

A. 10 years
B. 10.5 years
C. 11 years
D. 12 years