# SIMPLE INTEREST

Ans .

8500

1. Explanation :

P= Rs.6800,R= 50/3%p.a and T =9/12years=3/4 years.

S.I=(P*R*T)/100=Rs(68,000*(50/3)*(3/4)*(1/100))=Rs.8500

Ans .

37.50

1. Explanation :

2. Time = (24+31+18)days = 73 days = 73/365 years = 1/5 years. P = Rs.3000 and R = 6 1/4%p.a = 25/4%p.a

S.I. = Rs.(3,000*(25/4)*(1/5)*(1/100))= Rs.37.50.

Ans .

1625

1. Explanation :

Let sum be Rs. x then , S.I.=Rs.(x$$\frac{27}{2}$$*4*(1/100) ) = Rs.27x/50

amount = (Rs. x+$$\frac{27x}{50}$$ = $$\frac{77x}{50}$$

$$\frac{77x}{50}$$ = 2502.50

x = $$\frac{2502.50x50}{70}$$

= 1625 Hence , sum = Rs.1625.

Ans .

992

1. Explanation :

S.l. = Rs. (920 - 800) = Rs. 120; p = Rs. 800, T = 3 yrs.

R = ($$\frac{100 x 120}{(800*3)}$$ ) % = 5%. New rate = (5 + 3)% = 8%. New S.l. = Rs. $$\frac{(800*8*3)}{100}$$ = Rs. 192.

New amount = Rs.(800+192) = Rs. 992.

Ans .

12,000

1. Explanation :

Let the sum borrowed be x.

Then,$$\frac{(x*2*6)}{100}$$ + /(/frac{(x*9*3)}{100}\) + $$\frac{(x*14*4)}{100}$$= 11400

(3x/25 + 27x/100 + 14x / 25) = 11400

95x/100 = 11400 ? x = (11400*100)/95 = 12000.

Hence , sum borrowed = Rs.12,000.

Ans .

208 ,13%

1. Explanation :

S.I. for 1 1/2 years = Rs.(1164-1008) = Rs.156.

S.l. for 2 years = Rs.(156*(2/3)*2)=Rs.208

Principal = Rs. (1008 - 208) = Rs. 800.

Now, P = 800, T = 2 and S.l. = 208.

Rate=(100* 208)/(800*2)% = 13

Ans .

6$$\frac{1}{4}$$% p.a

1. Explanation :

Let principal = P. Then, S.l. = P and T = 16 yrs.

Rate = (100 x P)/(P*16)% = 6$$\frac{1}{4}$$% p.a.

Ans .

6$$\frac{2}{3}$$% p.a., 6 yrs 8 months

1. Explanation :

Let sum = Rs. x. Then, S.l. = Rs. 4x/9

Let rate = R% and time = R year.

Then, (x*R*R)/100=4x/9 or $$R^2$$ =400/9 or R = 20/3 = 6 2/3.

Rate = 6$$\frac{2}{3}$$ % and Time = 6$$\frac{2}{3}$$ = 6 years 8 months.

Ans .

800

1. Explanation :

Let the sum be Rs. x Then,$$\frac{x*10*7}{100*2}$$ - $$\frac{x*12*5}{100*2}$$ = 40

$$\frac{7x}{20}$$-$$\frac{3x}{10}$$=40

x = (40 * 20) = 800.

Hence, the sum is Rs. 800.

Ans .

6000

1. Explanation :

. Let sum = P and original rate = R.

Then, [ $$\frac{(P*(R+2)*3)}{100}$$]-[$$\frac{(P*R*3)}{100}$$] = 360.

3PR + 6P - 3PR = 36000

6P=36000

P=6000

Hence, sum = Rs. 6000

Ans .

325

1. Explanation :

.Let each Instalment be Rs. x

Then, ( x+ $$\frac{x*12*1}{100}$$ + x$$\frac{(x*12*2)}{100}$$ + x = 1092

((28x/25) + (31x/25) + x) = 1092

(28x+31x+25x)=(1092*25)

x= (1092*25)/84 = Rs.325. Each instalment = Rs. 325.

Ans .

650 ,900

1. Explanation :

Let the sum lent at 8% be Rs. x and that at 6% be Rs. (1550 - x).

$$\frac{x*8*1}{100}$$ + $$\frac{(1550-x)*6*1}{100}$$=106

8x + 9300-6x=10600

2x = 1300 x = 650.

Money lent at 8% = Rs. 650. Money lent at 6% = Rs. (1550 - 650) = Rs. 900.