In how many years will Rs. 1800 amount to Rs. 2178 at 10% per annum when compounded annually?
Let time = n years
P = Rs.1800
A = Rs.2178
R = 10% per annum
Now,
Amount (A) = P (1 + R/100)n [Where, A = Amount with compound interest
P = Present value
R = Annual interest rate
n = Time in years]
∴ A = P (1 + R/100)n
⇒ 2178 = 1800 (1 + 10/100)n
⇒ (1 + 1/10)n = 2178/1800
⇒ (11/10)n = 121/100
⇒ (11/10)n = (11/10)2
⇒ n = 2
∴ Time = 2 years.