First four terms of a series are 4, 12, 36, 108. What will be the 6^th term of this series?

Question

Question

This question was previously asked in

RRB NTPC CBT 2 (Level-3) Official Paper (Held On: 14 June 2022 Shift 1)

Answer 1

Given:

The series is 4, 12, 36, 108

Concept used:

In geometric progression

a_n = a₁{r^{(n - 1)}}

Here,

a_n = nth term

a₁ = 1st term

r = common ratio

n = number of term

Calculation:

According to the question:

a₁ = 4

a₂ = 12

So, common ratio of a₁ : a₂ = 4 : 12

⇒ 1 : 3

So,

a₆= 4 × 3^{(6 - 1)}

⇒ a₆ = 4 × 3⁵

⇒ a₆ = 4 × 243

⇒ a₆ = 972

So, 6^th term of the series = 972

∴ The 6^th term of this series is 972.

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