Aptitude | Arithmetic Aptitude 4 | Question 2

How many terms are there in 3,9,27,81……..531441?

(A) 25
(B) 12
(C) 13
(D) 14


Answer: (B)

Explanation:

3, 9, 27, 81..............531441 form a G.P. 
with a = 3 and r = 9/3 = 3
Let the number of terms be n

According to the formula,

N^th term of the G.P is represented as T_n = a x r^n-1

Then 3 x 3n-1 = 531441
∴ 3n = 312
∴ n = 12

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