 # S.I. & C.I. (6)

1. David invested certain amount in three different schemes A, B and C with the rate of interest 10% p.a., 12% p.a. and 15% p.a. respectively. If the total interest accrued in one year was Rs. 3200 and the amount invested in Scheme C was 150% of the amount invested in Scheme A and 240% of the amount invested in Scheme B, what was the amount invested in Scheme B?
1. Rs.5000
2. Rs.2000
3. Rs.6000
4. Rs.3000

Explanation :- 2. A sum of Rs. 1550 was lent partly at 5% and partly at 8% p.a. simple interest. The total interest received after 3 years was Rs. 300. The ratio of the money lent at 5% to that lent at 8% is:
1. 16 : 15
2. 15 : 16
3. 15 : 8
4. 8 : 15

Explanation :-

Lets suppose Part of Money lent on 5% be x & part of Money lent on 8% =(1550-x)
SI on x + SI on (1550-x) = 300
[(x*5*3)/100] + [((1500 – x )*8*3)/100] = 300
5x + 8(1500 – x) = 10000
3x = 2400
x = 800

3. A sum of money doubles in 12 years. In how many years, it will treble at S.I.
1. 12 years
2. 8 years
3. 6 years
4. 24 years

Explanation :-

Let the sum of money be x
As money is doubled in 12 years i.e.(2x) ,  Therefore , SI = 2x-x =x
SI=(P*R*T)/100
x=x*R*12/100
R=100/12
If money triples itself, Therefore SI = 3x – x = 2x
2x=x*(100/12)*T
=> T = 24 years

4. A man invests a certain sum of money at 6% per annum simple interest and another sum at 7% per annum simple interest. His income from interest after 2 years was Rs. 354. One-forth of the first sum is equal to one-fifth of the second sum. The total sum invested was :
1. Rs.3100
2. Rs.2700
3. Rs.2200
4. Rs.1800

Explanation :- 5. The interest on a certain deposit at 5% per annum is Rs. 101.20 in one year. How much will the additional interest in one year be on the same deposit at 6% per annum?
1. Rs.20.8
2. Rs.19.74
3. Rs.20.24
4. Rs.19.5