Answer:

Given:

Rs. 12000 becomes double of itself in 5 years when it is compounded.

Formula used:

Amount(A) = P[1 + (R/100)]T

P = Principal

R = Rate of interest

T = Time

Calculation:

P = Rs. 12000

According to the question:

2P = P[1 + (R/100)]5

⇒ 2 = [1 + (R/100)]5

If it is deposited for 20 years, then amount will be given by:

A = P[1 + (R/100)]20

⇒ A = 12000[1 + (R/100)]5 × 4

in⇒ A = 12000(2)4

⇒ A = 12000 × 16 = 192000

∴ The amount will become Rs. 192000 in 20 years