Simple Interest(Quantitative Aptitude > Interest ) Questions and answers for exam Preparation

Quantitative Aptitude > Interest

SIMPLE INTEREST MCQs

Total Questions : 234 | Page 9 of 24 pages

Question 81. A sum of Rs.1600 gives a simple interest of Rs.252 in 2 years and 3 months. The rate of interest per annum is:

8%
5$1/2$%
6%
7%

Discuss Question

Answer: Option D. -> 7%
Answer: (d)Using Rule 1,Principal (P) = Rs.1600T = 2 years 3 months= $(2 + 3/12) yrs. = (2 + 1/4) yrs. = 9/4 yrs.$S.I = Rs.252R = % rate of interest per annumR = ${100 × S.I.}/{P × t}$= ${100 × 252}/{1600 × 9/4}$Rate of interest = 7% per annum.

Question 82. If the annual rate of simple interest increases from 10% to 12$1/2$% , a man's yearly income increases by Rs.1250. His principal (in rupees) is

45,000
50,000
65,000
60,000

Discuss Question

Answer: Option B. -> 50,000
Answer: (b)Using Rule 1,Change in SI= $(25/2 - 10)% = 5/2%$$5/2$% of principal = Rs.1250Principal = Rs.${1250 × 2 × 100}/5$ = Rs.50000

Question 83. A sum of Rs. 800 amounts to Rs.920 in 3 years at the simple interest rate. If the rate is increased by 3% p.a., what will be the sum amount to in the same period ?

Rs.962
Rs.992
Rs.982
Rs.942

Discuss Question

Answer: Option B. -> Rs.992
Answer: (b)Using Rule 1,Case I,S.I. = 920 - 800 = Rs.120Rate = ${\text"S.I." × 100}/\text" Principal × Time"$= ${120 × 100}/{800 × 3}$ = 5% per annumCase II,Rate = 8% per annumS.I. = ${800 × 8 × 3}/100$ = Rs.192Amount = Principal + S.I.= (800 + 192) = Rs.992

Question 84. A person who pays income tax at the rate of 4 paise per rupee, find that a fall of interest rate from 4% to 3.75% diminishes his net yearly income by Rs.48. What is his capital ?

Rs.25,000
Rs.24,000
Rs.18,000
Rs.20,000

Discuss Question

Answer: Option D. -> Rs.20,000
Answer: (d)If the capital after tax deduction be x, thenx × (4 - 3.75) % = 48${x × 0.25}/100$ = 48${x × 25}/10000$ = 48$x/400$ = 48x = 48 × 400 = Rs.19200Required capital= ${19200 × 100}/96$ = Rs.20000

Question 85. A sum was invested on simple interest at a certain rate for 2 years. Had it been put at 3% higher rate, it would have fetched Rs.72 more. The sum is

Rs.1,500
Rs.1,200
Rs.1,800
Rs.1,600

Discuss Question

Answer: Option B. -> Rs.1,200
Answer: (b)Let the sum = P and original rate = R% per annum.Then, ${P × (R + 3) × 2}/100 - {P × R × 2}/100 = 72$${P × 3 × 2}/100 = 72$P = ${72 × 100}/{3 × 2}$ = Rs.1200 Using Rule 13The difference between the S.I. for a certain sum $P_1$ deposited for time $T_1$ at $R_1$ rate of interest and another sum $P_2$ deposited for time $T_2$ at $R_2$ rate of interest isS.I. = ${P_2R_2T_2 - P_1R_1T_1}/100$

Question 86. A certain sum of money becomes three times of itself in 20 years at simple interest. In how many years does it become double of itself at the same rate of simple interest ?

10 years
8 years
14 years
12 years

Discuss Question

Answer: Option A. -> 10 years
Answer: (a)Case-ILet the principal be xAmount = 3xInterest = 2xTime = 20 yearsI = $\text"PRT"/100$2x = ${x × R × 20}/100$ ⇒ R = 10%Case-III = x, P = x, R = 10, T = ?I = $\text"PRT"/100$x = ${x × 10 × T}/100$ ⇒ T = 10 years.Using Rule 3,R% = ${(3 - 1)}/20$ × 100% = 10%Now, T = ${(n - 1)}/R$ yearsT = ${2 - 1}/10 × 100$ = 10 years

Question 87. If a sum of money deposited in a bank at simple interest is doubled in 6 years, then after 12 years, the amount will be

3 times the original amount
$5/2$ times the original amount
4 times the original amount
$7/2$ times the original amount

Discuss Question

Answer: Option A. -> 3 times the original amount
Answer: (a)Case I,Principal = Rs.xInterest = Rs.xTime = 6 yearsRate = ${Interest × 100}/\text"Principal × Time"$= ${x × 100}/{x × 16} = 50/3%$ per annumCase II,Interest = ${x × 12 × 50}/{100 × 3}$ = Rs.2xi.e., Amount is thrice the principal.

Question 88. In how much time, will a sum of money become double of itself at 15% per annum simple interest?

6$1/2$ years
6$1/4$ years
6$2/3$ years
6$1/3$ years

Discuss Question

Answer: Option C. -> 6$2/3$ years
Answer: (c)If the principal be x, the amount = 2xSI = xTime = ${SI × 100}/\text"Principal × Rate"$= ${x × 100}/{x × 15} = 20/3 = 6{2}/3$ yearsUsing Rule 3,T = ${(n - 1)}/R × 100%$= $({2 - 1}/15) × 100$= $100/15 = 20/3$ Years= 6$2/3$ years

Question 89. In how many years will a sum of money double itself at 12% per annum?

6 yrs. 9 months
8 yrs. 6 months
7 yrs. 6 months
8 yrs. 4 months

Discuss Question

Answer: Option D. -> 8 yrs. 4 months
Answer: (d)If the principal be Rs.100 then S.I. = Rs.100.Time = ${SI × 100}/\text"Principal × Rate"$= ${100 × 100}/{100 × 12} = 25/3$ years= 8 years 4 monthsUsing Rule 3,T = ${(n - 1)}/R × 100%$= ${(2 - 1)}/12 × 100%$= $100/12 = 25/3$ years.= 8$1/3$ years= 8 years, 4 months.

Question 90. At what rate per cent per annum will the simple interest on a sum of money be $2/5$ of the amount in 10 years ?

6%
4%
6$2/3$%
5$2/3$%

Discuss Question

Answer: Option C. -> 6$2/3$%
Answer: (c)Using Rule 1Simple Interest (S.I.)= ${\text"Principal × Rate × Time"/100$ orS.I. = ${\text"P × R × T"/100$P = ${\text"S.I." × 100}/\text"R × T"$, R = ${\text"S.I." × 100}/\text"P × T"$, T = ${\text"S.I." × 100}/\text"P × R"$ A = P + S.I. or S.I. = A - P