S.I. or C.I. for first year are always equal
Principle = (S.I. x 100)/(Rate x Time)
= (48 x 100)/(8 x 1) = Rs. 600
Interest for second year = Amount of second year - Amount of the first year
= 600 (1 +8/100)2 - 600(1 +8/100)
= 600(27/25)2 - 600(27/25)
= 600(27/25) {27/25 - 1}
= 600(27/25) (2/25)
= Rs. 51.84
Yearly interest = 10%
Half yearly = 5%
Time = 11/2 = (3/2) x 2 half yearly = 3 half yearly
Amount = 8000(1 + 5/100)3
= 8000 x (21/20)3
= 8000 x 21/20 x 21/20 x 21/20
= Rs. 9261
Compound interest = Amount - Principal = 9261 - 8000
= Rs. 1261
Let the principal be P,then
P(1 + R/100)3 = 6690
And P(1 + R/100)6 = 10,035
Now, dividing (ii)by (i),we get
? (1 + R/100)3 = 10035/6690 = 3/2
? P x 3/2 = 6690
? P = (6690 x 2/3 ) = Rs. 4460
? [5000 x (1 +R/100)2 - 5000] - (5000 x 2 x R)/100 =72
? 5000[(1 +R/100)2 - 1 - R/50] = 72
? 1 + R2/10000 + 2R/100 - 1 - R/5 = 72/5000
? R2 = (72/5000 x 10000) = 144
? R = 12%
S.I. on Rs. 500 for 1 year = 540 - 500 = Rs. 40
? Rate = (100 x 40)/(500 x 1) = 8%
and Sum = Rs.(100 x 500)/(8 x 1) = Rs. 6250
Let P be the principle and R% per annum be the rate. Then,
P(1 + R/100)3 = 10648 ....(i)
and P(1 + R/100)2 = 9680 .....(ii)
on dividing (i) by (ii), we have
? (1 + R/100) = 10648/9680
? R/100 =968/9680 = 1/10
? R =100/10 = 10%
? 328 = Principal {(1 +5/100)2 - 1}
? 328 = Principal (441/400 - 1)
? 328 =Principal 41/400
? Principal = (328 x 400)/41 = Rs. 3200
? Simple interest = (3200 x 5 x 2) / 100 = Rs. 320
Here P(1 + 20/10)t > 2P
? (6/5)t > 2
? (6/5)3 = 1.728, and
(6/5)4 = 2.0736
By trial (6/5) x (6/5) x (6/5) x (6/5) > 2
? The required time is 4 years.
Clearly the difference between Rs. 578.40 and Rs.614.55 is the interest on Rs. 578.40 for 1 year.
? Interest on Rs. 578.40 for 1 year = Rs. 614.55 - Rs. 578.40 = Rs. 36.15
? Interest on Rs.100 for 1 year = Rs. (36.15 x 100)/578.40
= Rs. 3615/57840 x 100/1
= Rs. 6.25
= Rs. 61/4
? The required rate is .61/4 percent.
S.I. = Rs. (600 x 5 x 2)/100 = Rs.60
C.I.= Rs. [600 x (1 + 5/100)2 - 600] = Rs. 61.50
? Requred Difference = Rs. (61.50 - 60) = Rs.1.50
? P (1 - 10/100)3 = 729
? P = Rs.(729 x 10 x 10 x 10)/(9 x 9 x 9) = Rs. 1000
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