Question

The average mark of $13$ papers is $40.$ The average mark of the first $7$ papers is $42$ and that of the last seven papers is $35.$ Then the marks obtained in the $7^{\text{th}}$ paper is

• A. $21$
• B. $18$
• C. $23$
• D. $19$

Answer 1

The correct option is D $19$

The average of $13$ papers is $40.$
So, the sum $=13\times 40=520$
The average of first $7$ papers is $42.$
So, the sum $=7\times 42=294$
The average of last $7$ papers is $35$
So, the sum $=7\times 35=245$
Now, the marks obtained in the $7^{\text{th}}$ paper $=(294+245)-520=19$