Question

5. A sum of money amounts to 1150 in 3 years and to
1250 in 5 years at a certain rate per cent p.a. simple
interest. The rate per cent p.a. will be:
(a) 5%
(6) 8%
(C) 7%
(d) 6%
(e) None of these
​

Answer 1

Answer:

5%

Step-by-step explanation:

amount in 3 years=1150,amount i 5 years=1250                                                                                       simple interest in 2 years=1250-1150=100                                                           simple interest in 1 year= 100/2=50                                                                    simple interest in 3 years=50*3=150                                                                           principal=Amount-Simple interest=1150-150=1000                                               R=S.I*1000/P*T                                                                                                                            R=150*100/1000*3

R=15/3=5%

Answer 2

Answer:cholr Login

5 A shim of money amounts to R 1150 in 3 years and to ? 1250 in 5 years at a certain rate per cent p.a. simple interest. The rate per cent p.a. will be

Mathematics

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1 Answers

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Meera Mistry

Grade 11

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Let the rate of interest be r% and the principal be Rs.P

We know, Interest = (Principal*Rate*Time)/100

According to the problem, in 3 years,

1150-P = (P * 3 * r) / 100;

i.e., (1150-P)/3 = (P*r)/100 ....... this be equation (i)

According to the problem, in 5 years,

1250-P = (P * 5 * r) / 100;

i.e., (1250-P)/5 = (P*r)/100 ....... this be equation (ii)

Comparing equations (i) and (ii), we get:

(1150-P)/3 = (1250-P)/5

i.e., 5*(1150-P)=3*(1250-P);

i.e., 5750 - 5P = 3750 - 3P

i.e., 2P = 2000

i.e., P = Rs. 1000

Putting this value of P in equation (i), we get the value of r

i.e., (1150-P)/3 = (P*r)/100

i.e., 150/3 = (1000*r)/100

i.e., 50 = (10*r)

i.e., r = 5 %

Ans: Rate = 5%

Step-by-step explanation: