Aptitude - Compound Interest

Each of the questions given below consists of a question followed by three statements. You have to study the question and the statements and decide which of the statement(s) is/are necessary to answer the question.

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 Rs. 400.

 III. 

Simple interest earned per annum is Rs. 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         PR2 = 4000000.
100 100

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).


2. 

What will be the compound interest earned on an amount of Rs. 5000 in 2 years?

I. 

The simple interest on the same amount at the same rate of interest in 5 years is Rs. 2000.

II. 

The compound interest and the simple interest earned in one year is the same.

 III. 

The amount becomed more than double on compound interest in 10 years.

A. I only
B. I and II only
C. II and III only
D. I and III only
E. None of these

Answer: Option A

Explanation:

P = Rs. 5000 & T = 2 years.

I. S.I. on Rs. 5000 in 5 years is Rs. 2000.

   5000 x R x 5 = 2000         R = 8.
100

Thus I only gives the answer.

Correct answer is (A).