 # S.I. & C.I. (1)

1. How much time will it take for an amount of Rs. 900 to yield Rs. 81 as interest at 4.5% per annum of simple interest?
1. 2 years
2. 3 years
3. 1 year
4. 4 years

Explanation :-

P = Rs.900
R = 4.5%
SI = Rs.81
SI=(P*R*T)/100
Therefore ,
T=(100*SI)/(P*R)=(100*81)/(900*4.5)
=>2 years

2. Arun took a loan of Rs. 1400 with simple interest for as many years as the rate of interest. If he paid Rs.686 as interest at the end of the loan period, what was the rate of interest?
1. 8%
2. 6%
3. 4%
4. 7%

Explanation :-

Let rate = R%
Then, Time, T = R years
P = Rs.1400
SI = Rs.686
SI=(P*R*T)/100
680=(1400*R*R)/100
680=14R^2
R=7

3. A sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 854 in 4 years. The sum is :
1. Rs. 700
2. Rs. 690
3. Rs. 650
4. Rs. 698

Explanation :-

S.I. for 1 year = Rs. (854 – 815) = Rs. 39.
S.I. for 3 years = Rs.(39 x 3) = Rs. 117.
P= Rs. (815 – 117) = Rs. 698.

4. A sum fetched a total simple interest of Rs. 929.20 at the rate of 8 p.c.p.a. in 5 years. What is the sum?
1. Rs. 2323
2. Rs. 1223
3. Rs. 2563
4. Rs. 2353

Explanation :-

SI = Rs.929.20      T = 5 years    R = 8%
SI=(P*R*T)/100
Therefore
P=(SI*100)/(R*T)
P=(929.20*100)/(8*5)
P= Rs.2323

5. Mr. Thomas invested an amount of Rs. 13,900 divided in two different schemes A and B at the simple interest rate of 14% p.a. and 11% p.a. respectively. If the total amount of simple interest earned in 2 years be Rs. 3508, what was the amount invested in Scheme B?
1. Rs. 6400
2. Rs. 7200
3. Rs. 6500
4. Rs. 7500

Explanation :-

Let’s Suppose the investment in scheme A be Rs.x
Therefore,
The investment in scheme B be Rs.(13900 – x)
SI for Rs. x = (x*14*2)/100=28x/100
SI for Rs. (13900-x) = ((13900-x)*11*2)/100
=>(22 (13900 – x )/100)
Total SI= 3508, Therefore
(28x/100)+(22(13900 – x )/100) =3508
28x+305800-22x=350800
6x=45000
x=7500
Investment in scheme B = 13900 – 7500 = Rs.6400