Question

If, then the value of$n$ is.

• A. 35
• B. 36
• C. 37
• D. 40

Answer 1

Answer: (A)

35

Answer 2

We have

$\Rightarrow \frac { \frac { n } { 2 } [ 6 + ( n - 1 ) 2 ] } { \frac { 10 } { 2 } [ 10 + ( 10 - 1 ) 3 ] } = 7 \Rightarrow \frac { n ( 2 n + 4 ) } { 10 \times 37 } = 7$

$\Rightarrow$ $n ^ { 2 } + 2 n - 1295 = 0 \Rightarrow ( n + 37 ) ( n - 35 ) = 0$

Hence $n = 35$.