1.  The difference between the compound interest and the simple interest accrued on an amount of ₹ 18,000 in 2 year was ₹ 405. What was the rate of interest p.c.p.a ?
A. 15%
B. 12%
C. 10%
D. 13%

Answer: Option A

Explanation:

Let the rate be R% p.a. Then,

18000 x 1 + R 2 - 18000 - 18000 x R x 2
100 100

⇒ 405

⇒ 18000 1 + R 2 - 1 - 2R = 405
100 100

⇒ 15000 (100 + R)2 - 10000 - (200 x R) = 405
10000

⇒ R2 = 405 x 5 = 225
9

⇒ R = 15.

∴ Rate = 15%.