1. A sum of money deposited at compound interest doubles itself in 4 years. It will amount to sixten times at the same rate in

A. 12 years B. 16 years C. 24 years D. 30 years

Answer - Option B
Explanation -
Let sum = Rs. 100, Time = 4 years,
Amount due in 4 years = Rs. 200
i.e, [latex]100 ({1 + \frac {10} {100}}^{4})[/latex]
[latex] ({1 + \frac {10} {100}}^{4})[/latex] = 2 .....(i)
Let the amount becomes 16 times in n years
i.e, [latex]100 ({1 + \frac {10} {100}}^{n})[/latex] = 1600 ........(ii)
[latex] ({1 + \frac {10} {100}}^{n})[/latex] = 16
From equation (i) and (ii)
[latex]{2}^{\frac {1} {4}}[/latex] = 16 = [latex] {2}^{4}[/latex]
[latex]\frac {n} {4}[/latex] = 4
n = 16
2. For how many years should Rs. 1200 be invested at 10% p.a. in order to earn the same simple interest as is earned by investing Rs. 1800 at 12% p.a. for 5 years ?

A. 9 B. 10 C. 12 D. 11

Answer - Option A
Explanation -
S.I. required = Rs [latex]\frac {1800 * 12 * 5} {100}[/latex]
= Rs. 1080.
[latex]\frac {100 * 1080} {120 * 10}[/latex] = 9 years
3. A sum of money was lent at simple interest at 11% p.a. for 3[latex]\frac {1} {2}[/latex] years and 4 [latex]\frac {1} {2}[/latex] years respectively. If difference in interests for two periods was Rs.5500, then the sum is

A. Rs. 50050 B. Rs. 55000 C. Rs. 50000 D. Rs. 50500

Answer - Option C
Explanation -
Let the sum Rs. x. Then
(x * 11 * [latex]\frac {9} {2}[/latex] * [latex]\frac {1} {100} - x * 11 \frac {7} {2} * \frac {1} {100}[/latex]) = 5500
[latex]\frac {22x} {200}[/latex] = 5500
11x = 550000
x = 50000
4. Rajan lent Rs. 1200 to Rakesh for 3 years at a certain rate of simple interest and Rs. 1000 to Mukesh for the same time at the same rate. If he gets Rs. 50 more from Rakesh than from Mukesh, then the rate percent is

A. 8 [latex]\frac {1} {3}[/latex] % B. 6 [latex]\frac {2} {3}[/latex] % C. 10 [latex]\frac {1} {3}[/latex] % D. 9 [latex]\frac {2} {3}[/latex] %

Answer - Option A
Explanation -
[latex]\frac {1200 * r * 3} {100}[/latex] - [latex]\frac {1000 * r * 3} {100}[/latex] = 50
6r = 5o
r = 8 [latex]\frac {1} {3}[/latex]%
5. The difference between interests received from Canara Bank and Punjab & Sind Bank on Rs. 500 for 2 years is Rs. 2.50. The difference between their rates is

A. 1 % B. 0.5% C. 0.25% D. 2.5%

Answer - Option C
Explanation -
[latex]\frac {500 * {r}_{1} * 2} {100}[/latex] - [latex]\frac {500 * {r}^{2} * 2} {100}[/latex] = 2. 50
1000 ([latex]{r}_{1} - {r}_{2}[/latex]) = 250
([latex]{r}_{1} - {r}_{2}[/latex])[latex]\frac {250} {1000}[/latex]% = [latex]\frac{1}{4}[/latex] = 0.25%

1. If compound interest for two successive years is Rs. 110 and Rs. 121 respectively, then the rate of interest is

A. 10% B. 8% C. 6% D. 4%

Answer - Option A
Explanation -
In the first year, interest = Rs. 110
In the second year, interest = Rs. 121
Thus an additional interest of Rs. 11 is earned in the second year. This additional interest is earned on the interest earned in first year i.e., on Rs. 110.
i.e, Rate of interest [latex]\frac {11 * 100} {110 * 1}[/latex] = 10%
2. A money lender finds that due to a fall in the rate of interest from 8% to 7 [latex]\frac {3} {4}[/latex] %, his yearly income diminishes by Rs. 615. His capital is

A. Rs. 260000 B. Rs. 246000 C. Rs. 238000 D. Rs. 224000

Answer - Option B
Explanation -
Let the capital be Rs. x. Then
[latex]\frac {x * 8 * 1} {100}[/latex] - x [latex]\frac {31} {4}[/latex] * [latex]\frac {1} {100}[/latex] = 615
32x – 31x = 61500 * 4
x = 246000
3. Mr. Mittal finds that an increase in the rate of interest from 4 [latex]\frac {7} {8}[/latex] % to 5 [latex]\frac {1} {8}[/latex] % per annum increases his yearly income by Rs. 250. His investment is

A. Rs. 1,00,000 B. Rs. 1,20,000 C. Rs. 1,50,000 D. Rs. 2,00,000

Answer - Option A
Explanation -
Let the investment be Rs. x. Then
[latex]x * \frac {41} {8} * \frac {1} {100} - x \frac {39} {8} * \frac {1} {100}[/latex] = 250
2x = 20000
x = 100000
4. In how many years will a sum of money double itself at 4% per annum ?

A. 8 years B. 16 years C. 12 years D. 25 years

Answer - Option D
Explanation -
Let the sum be x. Then
S.I. = x
i.e, Time = [latex] \frac {100 * S.I} {Sum * Rate}[/latex] = [latex]x * \frac {100 * x} {x * 4}[/latex]
= 25 years
5. At a certain rate of simple interest, a certain sum doubles itself in 10 years. It will triple itself in

A. 12 years B. 15 years C. 20 years D. 30 years

Answer - Option C
Explanation -
Let the sum be x. Then
S.I. = x
Time = 10 years.
i.e, Rate = [latex] \frac {100 * x} {x * 10}[/latex]% = 10%
Now, sum = x, S.I. = 2x, Rate = 10%
i.e, Time = [latex]\frac {100 * 2x} {x * 10}[/latex]years = 20 years

1. The simple interest on rupees 200 for 3 years at 6% per annum in rupees is

A. 36 B. 18 C. 24 D. 48

Answer - Option A
Explanation -
SI = [latex]\frac {200 * 30 * 6} {100}[/latex] = Rs. 36
2. A sum of money doubles itself in 4 years when the interests is compounded annually. The number of years when it will become eight times is

A. 32 B. 16 C. 12 D. 8

Answer - Option C
Explanation -
If the money gets doubled in 4 years then it will become 5 times in 8 years and 8 times in 12 years.
3. The simple interest on rupees 800 for 7 years at 5% per annum is

A. Rs. 100 B. Rs. 125 C. Rs. 150 D. Rs. 200

Answer - Option A
Explanation -
Simple interest = [latex]\frac {PTR} {100}[/latex]
= 800 * [latex]\frac {5} {100} * \frac {5} {2}[/latex]
4. The compound interest on rupees 12000 for 1 year at 10% per annum compounded half yearly is

A. Rs. 1200 B. Rs. 1230 C. Rs. 2520 D. Rs. 2680

Answer - Option B
Explanation -
Compound interest for [latex]\frac {1} {2}[/latex]year = [latex]\frac {PTR} {100}[/latex]
= 12000 * [latex]\frac {10} {100} * \frac {1} {2}[/latex] = 600
Compound interest for next [latex]\frac {1} {2}[/latex]year = 600 + 600 * [latex]\frac {10} {100} * \frac {1} {2}[/latex] = 630
i.e, Total CL = 600 + 630
= Rs. 1230
5. The simple interest on rupees 800 for 3 years at 5% per annum in rupees is

A. 24 B. 40 C. 120 D. 140

Answer - Option C
Explanation -
SI = [latex]\frac {PTR} {100}[/latex]
SI = 800 * = [latex]\frac {5} {100} * 3[/latex] = 120