###
**How many terms are there in the GP 5, 20, 80, 320……….. 20480?**

A. 5
B. 6
C. 8
D. 7
**Answer: Option D**

## Show Answer

Solution(By Apex Team)

Common ratio, r = $\Large\frac{20}{5}$ = 4
Last term or nth term of GP = $a r^{n-1}$
$\begin{aligned}&20480=5\times\left(4^{n-1}\right)\\
&\text{ Or, }4^{n-1}=\frac{20480}{5}=4^8\end{aligned}$
So, comparing the power,
Thus, n – 1 = 8
Or, n = 7
Number of terms = 7

## 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