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**The first term of an Arithmetic Progression is 22 and the last term is -11. If the sum is 66, the number of terms in the sequence are:**

A. 10
B. 12
C. 9
D. 8
**Answer: Option B**

## Show Answer

Solution(By Apex Team)

Number of terms = n (let)
First term (a) = 22
Last term (l) = – 11
Sum = 66
Sum of an AP is given by:
$\begin{aligned}&=\text{ Number of terms }\times\frac{\text{ First term }+\text{ Last term }}{2}\\
&66=\mathrm{n}\times\frac{\mathrm{a}+\mathrm{l}}{2}\\
&66=\mathrm{n}\times\frac{22-11}{2}\\
&66=\mathrm{n}\times\frac{11}{2}\\
&\mathrm{n}=\frac{66\times2}{11}\\
&\mathrm{n}=12\\
&\text{No. of terms}=12\end{aligned}$

## Related Questions On Progressions

### How many terms are there in 20, 25, 30 . . . . . . 140?

A. 22B. 25

C. 23

D. 24

### Find the first term of an AP whose 8th and 12th terms are respectively 39 and 59.

A. 5B. 6

C. 4

D. 3

### Find the 15th term of the sequence 20, 15, 10 . . .

A. -45B. -55

C. -50

D. 0

### The sum of the first 16 terms of an AP whose first term and third term are 5 and 15 respectively is

A. 600B. 765

C. 640

D. 680