Aptitude - Simple Interest - Discussion

@Satyajit das.

You said that si= (p*102/100*R*7)/100.

How it will come?

Mainly I want the number 102 from where it has come?

That equation 2 is also same doubt.

Can you explain me briefly?

For all those who are solving the problem using "2% of R" , R being the Rate of Interest, its not given so in the problem. It's given as 2% more..not 2% of R.

I had been trying to solve using this method and was getting answer as 350.

Then I realized the mistake and I am currently doing the problem as "R+2%".
Now I am not getting the answer since R is not known, as well as P(Principal).

In simple words..do the problem by "R+2%" not by "1.02R"
So the answer is D) Cannot be determined.

As rate of interest is 2% for 7 years it is 14%.

That's why there is increase in interest that is 1750(14%increase) = 1995.

The extra amount would be 1995-1750 = 245.

i = pxrxt/100.

pxr = (ix100)/t = 25000.

Now we have constant value of pxr.

Now if we are saying that the new rate is 2% more.

Than new rate = r+(2% of r) = r+(2r/100) = r(102/100) = 1.02r.

When new are is 1.02r.

The i = px(new-r)xt/100.

i = px 1.02r x t/100 = (pxr x 1.02 x 7)/100.

We have pxr = 25000 (calculated in first step).

So i = 25000x1.02x7/100 = 1785.

So gain in interest = 1785-1750 = 35.

@Sparsh.

255-250 = 5.
5*7 years = 35.

That's the answer. Increase in simple interest.

Can't the answer be Rs. 255.

Since Rs. 1750 interest earned in 7 years means Rs. 250 interest earned in 1 year.

Now (P*R*T)/100 = SI.

For 1 year, it will be (P*R*1)100 = 250.

i.e P*R = 25000.

Now again, when rate increased by 2%.

For 1 year, it will be (P*102R/100*1)/100 = ?

i.e (P*R*102/100)100 = ?

Putting P*R = 25000 from above.

(25000*102/100)100 gives Rs. 255.

Please correct me if I'm wrong but this is what I think.

Let the rate of S.I is 100 (initially).

In the first case:

Sum = (S.I x 100)/(Rate of interest x time).

So sum = (1750 x 100)/(100 x 7) = 250.

In the 2nd case:

The interest rate is 2% more, so the interest rate is 102%.

S.I = (sum x time x Rate of interest)/100.

= (250 x 7 x 102)/100 = 1785.

So the gain in S.I is (1785-1750) = 35.

Thank You.

Ans: B.

In the 1st case: S.I = 245R/2 (Let, R =Rate of Interest).

In the 2nd case: S.I = (245R/2+490/2).

So, in the 2nd case we have Rs.245 extra.

Hey friends I think the answer will be option A i.e. 35,

Explanation:

let r be 100,and it is increased by 2% for second case, so for the second case r will be 102.
I = Rs. 1750, t=7 yrs, r=100(let).

So P = (I*100)/r*t=(1750*100)/(100*7) = 250.

So use this P for the second case,and S.I will be,
I = (P*t*r)/100=(250*7*102)/100 = 1785.

So the increase will be = Rs.(1785-1750) = Rs.35.

Hey friends it was said that when no principal amount given then take 100 =p so why we can't write this value.