Simple Interest Questions and Answers

Q: 1/5 part of an amount was given at 3% simple interest, 1/3 part was given at 5% simple interest, 2/5 parts at 9% simple interest and remaining part at 11% simple interest. The total interest received was Rs.297. How much amount was originally given?

\[ \text{SI} = \frac{P \times R \times T}{100} \]The four parts must account for the whole, so the last fraction is\[ 1 - \frac{1}{5} - \frac{1}{3} - \frac{2}{5} = \frac{15 - 3 - 5 - 6}{15} = \frac{1}{15} \]Adding the four interests for one year:\[ \frac{P}{100}\left(\frac{3}{5} + \frac{5}{3} + \frac{18}{5} + \frac{11}{15}\right) = 297 \]\[ \frac{P}{100} \times \frac{9 + 25 + 54 + 11}{15} = \frac{P}{100} \times \frac{99}{15} = 297 \]\[ P = \frac{297 \times 1500}{99} = \text{Rs. } 4500 \]The three named fractions come to \( \tfrac{14}{15} \), so the unnamed remainder is \( \tfrac{1}{15} \) - easy to overlook.

Q: The difference between the simple interest received from two different sources on Rs. 1500 for 3 years is Rs. 13.50. The difference between their rates of interest is?

\[ \text{SI} = \frac{P \times R \times T}{100} \]The sum and the period are common, so only the gap in rates produces the difference.\[ \frac{1500 \times \Delta R \times 3}{100} = 13.50 \]\[ 45\,\Delta R = 13.50 \quad\Longrightarrow\quad \Delta R = 0.3\% \]Neither rate needs to be known individually - only their difference enters the calculation.

Q: In how much time would the simple interest on a certain sum be 0.125 times the principal at 10% per annum?

\[ \text{SI} = \frac{P \times R \times T}{100} \]\[ 0.125P = \frac{P \times 10 \times T}{100} = 0.1PT \]\[ T = \frac{0.125}{0.1} = 1.25 = 1\tfrac{1}{4} \text{ years} \]At 10% a year, interest of 12.5% of the sum takes a year and a quarter.

Important Instructions

131.

The simple interest accrued on an amount Rs.10,000 at the end of two years is same as the compound interest on Rs.8,000 at the end of two years. The rate of interest is same in both the cases. What is the rate of interest?

A.100% p.a.
B.200% p.a.
C.300% p.a
D.50% p.a.

Answer: D

Given that Rs.10,000 is invested in S.I for two years and Rs.8,000 in C.I for two years

=> C.I - S.I

=> 8,000 { [1 + r/100]2 - 1} = (10,000)2r /100

=> 8{ 1 + 2r/100 + r2 / (100)2 - 1} = r/5

=> 16r/100 + 8r2/(100)2 = 20r/100

=> 4r/10 = 8r2/(100)2

=> 8[r/100]2 - 4r/100 = 0

=> r/100 {8r/100 -4} = 0

=> r = 0% of 50%

Since r!= 0%, r =50%

Discuss in Forum

132.

1/5 part of an amount was given at 3% simple interest, 1/3 part was given at 5% simple interest, 2/5 parts at 9% simple interest and remaining part at 11% simple interest. The total interest received was Rs.297. How much amount was originally given?

A.4500
B.5500
C.3950
D.4200

Answer: A

\[ \text{SI} = \frac{P \times R \times T}{100} \]

The four parts must account for the whole, so the last fraction is

\[ 1 - \frac{1}{5} - \frac{1}{3} - \frac{2}{5} = \frac{15 - 3 - 5 - 6}{15} = \frac{1}{15} \]

Adding the four interests for one year:

\[ \frac{P}{100}\left(\frac{3}{5} + \frac{5}{3} + \frac{18}{5} + \frac{11}{15}\right) = 297 \]

\[ \frac{P}{100} \times \frac{9 + 25 + 54 + 11}{15} = \frac{P}{100} \times \frac{99}{15} = 297 \]

\[ P = \frac{297 \times 1500}{99} = \text{Rs. } 4500 \]

The three named fractions come to \( \tfrac{14}{15} \), so the unnamed remainder is \( \tfrac{1}{15} \) - easy to overlook.

Discuss in Forum

133.

The difference between the simple interest received from two different sources on Rs. 1500 for 3 years is Rs. 13.50. The difference between their rates of interest is?

A.0.1%
B.0.2%
C.0.3%
D.0.4%

Answer: C

\[ \text{SI} = \frac{P \times R \times T}{100} \]

The sum and the period are common, so only the gap in rates produces the difference.

\[ \frac{1500 \times \Delta R \times 3}{100} = 13.50 \]

\[ 45\,\Delta R = 13.50 \quad\Longrightarrow\quad \Delta R = 0.3\% \]

Neither rate needs to be known individually - only their difference enters the calculation.

Discuss in Forum

134.

In how much time would the simple interest on a certain sum be 0.125 times the principal at 10% per annum?

A.1 1/4 years
B.1 3/4 years
C.2 1/4 years
D.2 3/4 years

Answer: A

\[ \text{SI} = \frac{P \times R \times T}{100} \]

\[ 0.125P = \frac{P \times 10 \times T}{100} = 0.1PT \]

\[ T = \frac{0.125}{0.1} = 1.25 = 1\tfrac{1}{4} \text{ years} \]

At 10% a year, interest of 12.5% of the sum takes a year and a quarter.

Discuss in Forum

Loading…

Topics

Other Subjects

Tags: Simple Interest Questions and Answers || Simple Interest MCQ Questions and Answers || Simple Interest GK Questions and Answers || Simple Interest GK MCQ Questions || Simple Interest Multiple Choice Questions and Answers || Simple Interest GK || GK on Simple Interest || Quantitative Aptitude Questions and Answers || Quantitative Aptitude MCQ Questions and Answers || Quantitative Aptitude GK Questions and Answers || GK on Quantitative Aptitude

Simple Interest Questions and Answers

Important Instructions

Topics

Other Subjects

About Us

Stay informed about all important Dates & Notifications