 # S.I. & C.I. (5)

1. In how many years, Rs. 150 will produce the same interest at 6% as Rs. 800 produce in 2 years at 4½% ?
1. 4 years
2. 6 years
3. 8 years
4. 9 years

Explanation :-

SI for Rs.150 at 6% for t years = SI for Rs.800 at 4½ % for 2 years
(150*6*t)/100 = (800*(9/2)*2)/100
150*6*t = 800*9
t = (800*9)/(150*6)
t = 8 Years

2. A sum of Rs. 2500 amounts to Rs. 3875 in 4 years at the rate of simple interest. What is the rate of interest?
1. 12.25%
2. 12%
3. 6%
4. 13.75%

Explanation :-

P = Rs. 2500
T = 4 years
SI = 3875 – 2500 = Rs.1375
R = (SI*100)/(P*T)=(1375*100)/(2500*4)
R = 13.75%

3. What is the interest due after 40 days for Rs. 3200 at 10%
1. 35.07
2. 36.21
3. 35.52
4. 34

Explanation :-

P = 3200
R = 10%
T = 40/365 year
SI = (P*R*T)/100
SI = (3200*10*(40/365))/100
SI = Rs. 35.07

4. What is the rate of interest at which Rs.150 becomes Rs. 220 in 10 years.
1. 11/3%
2. 14/3%
3. 12%
4. 14%

Explanation :-

P = 150,  R = ? ,  T = 10 years
SI = 220-150 = 70
R = (SI*100)/(P*T)
R = (70*100)/(150*10)
R = 14/3 %

5. A person invested in all Rs. 2600 at 4%, 6% and 8% per annum simple interest. At the end of the year, he got the same interest in all three cases. The money invested at 4% is:
1. Rs.2200
2. Rs.800
3. Rs.1600
4. Rs.1200

Explanation :-

Let’s suppose the portions pf money invested be x, y and 2600 – (x + y)
Therefore,
SI for Part of money invested at 4% = SI for Part of money invested at 6% = SI for Part of money invested at 4%
(x * 4 * 1)/100 = (y * 6 * 1)/100 = [{2600 – (x + y) }* 8 * 1]/100
y/x = 4/6 = 2/3
or
y = 2/3 x
Therefore
(x * 4 * 1)/100 = [(2600 – 5/3 x) * 80/100] 52x = (7800 * 8)
=> x = 1200
Part of money invested at 4% = Rs. 1200.