Question

in how much time will the simple interest on a certain sum be rupees 168 if it produces rupees 21 as interest in 4 months at half the rate​

Answer 1

Answer:

time=1hr. 11/14min.

Step-by-step explanation:

principal = amount - simple intrest =168-21=147

rate=4/6*12p.a.=8p.a.

time=?2

si=p*r*t/100

21=147*8*t/100

(21*100)/(147*8)=t

100/56=t

t=(1)+44/56

=(1)+(11/14)

Answer 2

16 months

Step-by-step explanation:

Consider the sum of amount is P monthly rate of interest is r,

Then the amount of simple interest after t months,

$I=\frac{P\times r\times t}{100}$

if t = 4 months, r = r/2,

Interest would be,

$I=\frac{P\times \frac{r}{2}\times 4}{100}$

According to the question,

$\frac{P\times \frac{r}{2}\times 4}{100}=21$

$\frac{2Pr}{100}=21$

$2Pr = 2100$

$\implies Pr =\frac{2100}{2}=1050$

Thus, interest after t months,

$I=\frac{1050t}{100}$

If I = 168 rupees,

$168 =\frac{1050t}{100}$

$168 = \frac{21t}{2}$

$8\times 2=t$

$\implies t = 16$

Hence, after 16 months the interest would be 168.

#Learn more:

Principal amount=2500 inter 4•/• in 30 month found simple interest

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