### The 3rd and 7th term of an arithmetic progression are -9 and 11 respectively. What is the 15th term?

A. 28 B. 87 C. 51 D. 17 Answer: Option C

### Solution(By Apex Team)

$\begin{array}{l} T_{3}=a+2 d=-9 \ldots(1) \\ T_{7}=a+6 d=11 \ldots(2) \\ \text { on solving }(1) \text { and }(2) \\ d=5 \& a=-19 \\ T_{15}=a+14 d \\ \quad=-19+14(5) \\ \quad=51 \end{array}$

A. 22
B. 25
C. 23
D. 24

A. 5
B. 6
C. 4
D. 3

A. -45
B. -55
C. -50
D. 0