# Simple Interest Quiz Set 020

### Question 1

The difference between simple interests on an amount @7% for 17 years and at 2% for 6 years is Rs. 535. What is the amount?

A

Rs. 500.

B

Rs. 600.

C

Rs. 400.

D

Rs. 700.

Soln.
Ans: a

The shortcut formula is P = ${\text"diff" × 100}/{r_1 × t_1 - r_2 × t_2}$. Putting r1 = 7, t1 = 17, r2 = 2, t2 = 6, diff = 535, we get P = Rs. 500.

### Question 2

A sum of Rs. 1540 is divided into two parts such that simple interest on these parts at 10% p.a. after 2 and 9 years, respectively, is same. What is the amount of the smaller part?

A

Rs. 280.

B

Rs. 380.

C

Rs. 180.

D

Rs. 480.

Soln.
Ans: a

We should use the shortcut technique here. If r1, t1, r2, t2 be the rates and times for two parts with same interest amount, then the two parts must be in the ratio $1/{r_1 t_1} : 1/{r_2 t_2}$. In our case r1 = r2 = 10, which cancels, so the ratio is $1/t_1 : 1/t_2$. Thus, the two parts are in the ratio $t_2 : t_1$. The parts are: 1540 × $9/{2 + 9}$, and 1540 × $2/{2 + 9}$, which are 1260 and 280. The smaller is Rs. 280.

### Question 3

Mr. X borrowed Rs. 500 from Mr. Y on simple interest @2% for 15 years. He then adds an amount x to it and lends it to Mr. Z @8% for the same duration. What is x if he gains Rs. 690?

A

Rs. 200.

B

Rs. 300.

C

Rs. 250.

D

Rs. 400.

Soln.
Ans: a

His gain is ${(500 + x) × 8 × 15}/100$ - ${500 × 2 × 15}/100$ = 690. We can solve this for x to get x = Rs. 200.

### Question 4

An investor puts an amount of Rs. 4600 in a simple interest scheme. If the rate of interest is 8%, how long does he have to wait for getting an amount of Rs. 5336?

A

2 years.

B

3 years.

C

5 years.

D

4 years.

Soln.
Ans: a

The interest is I = 5336 - 4600 = 736. So T = $(I × 100)/(R × P)$. Solving, we get T = $(736 × 100)/(8 × 4600)$ = 2 years.

### Question 5

What is the interest on Rs. 12500 @2% for 73 days starting from Jan 1, 3201?

A

Rs. 50.

B

Rs. 150.

C

Rs. 100.

D

Rs. 250.

Soln.
Ans: a

The given year is not a leap year. So it has 365 days. Since 73 X 5 = 365, t = 1/5 year. We have r = 2%, t = 1/5, P = 12500, so I = ${12500 × 2 × 1}/{5 × 100}$ = Rs. 50. 