# Simple Interest Quiz Set 012

### Question 1

The interest on Rs. 6000 @6% for a certain number of days starting from Jan 1, 1801 is Rs. 72. How many days?

A

73 days.

B

74 days.

C

72 days.

D

75 days.

Soln.
Ans: a

We have r = 6%, P = 6000, I = 72, so t = ${100 × 72}/{6000 × 6}$. We get t = 1/5. The given year is not a leap year. So it has 365 days. Since 365/5 = 73, the number of days is 73.

### Question 2

Simple interest on a certain sum of money is $1/2$ of the sum for 10 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/2, then $1/2$ = RT/100. So R = $100/{2 × 10}$ = 5%.

### Question 3

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

A

4%.

B

5%.

C

3%.

D

6%.

Soln.
Ans: a

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

### Question 4

Mr. X puts an amount of Rs. 800 in a simple interest scheme. If he gets a total amount of Rs. 1448 after 9 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 = 1448 - 800 = 648. So R = $(I × 100)/(T × P)$. Solving, we get R = $(648 × 100)/(9 × 800)$ = 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 5

The difference between simple interests on an amount @11% for 6 years and at 4% for 13 years is Rs. 126. What is the amount?

A

Rs. 900.

B

Rs. 1000.

C

Rs. 800.

D

Rs. 1100.

Soln.
Ans: a

The shortcut formula is P = ${\text"diff" × 100}/{r_1 × t_1 - r_2 × t_2}$. Putting r1 = 11, t1 = 6, r2 = 4, t2 = 13, diff = 126, we get P = Rs. 900. 