1. 

What is the rate of interest p.c.p.a.?

I. An amount doubles itself in 5 years on simple interest.

II. Difference between the compound interest and the simple interest earned on a certain amount in 2 years is ₹ 400.

III. Simple interest earned per annum is ₹ 2000.
A. I only
B. II and III only
C. All I, II and III
D. Any two of the three
E. I only or II and III only

Answer: Option E

Explanation:

  I. P x R x 5 = P         R = 20.
100

 II. P 1 + R 2 - P - P x R x 2 = 400     
100 100

⇒ PR2 = 4000000.

III. P x R x 1 = 2000         PR = 200000.
100

PR2 = 4000000         R = 20.
PR 200000

Thus I only or (II and III) give answer.

∴ Correct answer is (E).