Correct Answer - Option 3 : 1.5 years
Given:
Principal (P) = RS. 1000
Amount (A) = Rs. 1331
Rate % = 20%
Formula used:
Compound interest = P(1 + (R/100))t
Here, P = Principal, R = Rate, t = Time
Calculation:
According to question ,
Note: When interest is compound half -yearly.
Rate % = 20/2 = 10%
Time = 2t
By using formula,
⇒ 1331 = 1000(1 + (10/100))2t
⇒ 1331/1000 = (11/10)2t
⇒ (11/10)3 = (11/10)2t
By equating both sides
⇒ 2t = 3
⇒ t= 3/2 years
⇒ t = 1(1/2) years
∴ Time is 1.5 years