# Simple Interest Quiz Set 010

### Question 1

The simple interest on a certain principal sum @2% for a period of 4 years is Rs. 360. What is the sum?

A

Rs. 4500.

B

Rs. 4600.

C

Rs. 4400.

D

Rs. 4700.

Soln.
Ans: a

P = \$(I × 100)/(R × T)\$. Solving, we get P = \$(360 × 100)/(2 × 4)\$ = Rs. 4500.

### Question 2

Mr. X puts an amount of Rs. 2600 in a simple interest scheme. If he gets a total amount of Rs. 3770 after 5 months, what is the rate of interest?

A

\${3/4}\$% p.a.

B

9% p.a.

C

\${11/12}\$% p.a.

D

1% p.a.

Soln.
Ans: a

The interest is I = 3770 - 2600 = 1170. So R = \$(I × 100)/(T × P)\$. Solving, we get R = \$(1170 × 100)/(5 × 2600)\$ = 9% per month, which is \${3/4}\$% per annum. Please note that since the time is in months the rate is also p.m.

### Question 3

The simple interest on a hypothetical investment is Rs. 5120. What is the principal amount if the rate per annum, time in years and the principal, all have the same numerical value?

A

Rs. 80.

B

Rs. 180.

C

Rs. 130.

D

Rs. 280.

Soln.
Ans: a

If I is the interest, and principal is P, time is P, and rate is P, then, I = \$(P × P × P)/100\$. Which gives P = \$√^3{100 × I}\$, which is \$√^3{100 × 5120}\$, which is \$√^3{1000 × 8 × 8 × 8}\$ = Rs. 80.

### Question 4

A certain amount is split into two parts. The first part is invested at 10% p.a. and the second at 5% p.a. What is the total amount if the total simple interest at the end of 2 years is Rs. 240, and if the amount invested at 10% is Rs. 1400?

A

Rs. 1000.

B

Rs. 1100.

C

Rs. 900.

D

Rs. 1200.

Soln.
Ans: a

Let the amount x be invested at r1% and remaining (P - x) at r2%, and let the sum of interests be I. Then, I = \${x × r_1 × 2}/100\$ + \${(P - x) × r_2 × 2}/100\$, which simplifies to 100I = 2 × (\$x × (r_1 - r_2) + P × r_2\$). Putting r1 = 10, r2 = 5, x = 1400, I = 240, we get P = Rs. 1000.

### Question 5

Simple interest on a certain sum of money is \$1/4\$ of the sum for 5 years. What is the rate of interest?

A

5%.

B

6%.

C

4%.

D

7%.

Soln.
Ans: a

We know, I = PRT/100. If I = P/4, then \$1/4\$ = RT/100. So R = \$100/{4 × 5}\$ = 5%.