Aptitude - Compound Interest - Discussion

could any one explain it clearly..........

Hi @yoga,
its simple 1st we find out the C.I. on amount(4000)
later on, we half the interest on C.I. as per mention in the question and than we find out the S.I.

Hope it helps..

Could any one explain it clearly?

Hi Sandeep,

First find the C.I with the amount of Rs 4000.

Question itself mention that the amount of S.I is half the amount of C.I ......
then divide the amount of C.I by 2 and sub in S.I formula to find the principal amount....

Why we do 4000 minus?

@ishan.

You got the interest 4840 at the 4000rs. So the amount you put it in the business is 4000 and got the 4840. I hope you got it.

I donot understand till now why 4000 substact there and after that what is the formula of sum put there.

@Sipun

Formula for finding CI=Amount-Principal....
find out Amount using P(1+R/100)^n then subtract with Principal getting CI.In question itself given SI is half the CI so
SI=PTR/100;
CI/2=PTR/100;

Hi Questioners,

First if you know the how to calculate the compound intrest then it is easy. First of all calculate the compound intrest as for the given figures. If you use formula it gives the total amount with the intrest that was compunded.

After calculating the compuound intrest then half the compund intrest, that is the simple intrest of the first part of the Question then calculate the sum using the formula PTR/100=Half of the compund intrest.

Here we need to calculate the P then use the simple mathematical calculations.

You can get the answer.

Hi,

I have answer to queries,

Here the question is tricky.

Simple interest on certain sum= 1/2 of compound interest on 4000$.

It means interest only.

Simple interest(SI)= PNR &
Compound interest(CI) = P(1+r/n)^(nt)
Its interest on certain sum = SI-P or CI-P

That's why 4000$ is deduced in equation.