Aptitude - Simple Interest - Discussion

After 8 months, the principal should be 725+362.50, but it cannot be just 362.50.
Can you justify why is it just 362.50?

How to calculate 725*R*1/ 100 and how come 2175?

Please solve it Step By Step.

33.50 = ((R*725*8)/(100*12)) + ((2R*362.50*4)/(100*12)).
R = 6%.

3 * 725 = 2175.

How 2175? Why multiplied by 3.

Please someone explain.

How they take 725 for 1 year when the says the beginning of the year and after 8 months?

I think 725 is for 8/12 and 362.5 for 1/3.

Please suggest me.

725 x R x 1 + 362.50 x 2R x 1 = 33.50.
100 100 x 3.
(2175 + 725) R = 33.50 x 100 x 3,
(2175 + 725) R = 10050,
(2900)R = 10050.
R = 10050 = 3.46.
2900.

Original rate = 3.46%.

I agree @M.F Vinod.

This is the Correct Explanation.
SI is calculated for 8 months and then for the remaining 4 months. After 8 months an amount of Rs. 362.50 added to the principal and the rate to this added amount is 2R% and the time remaining in a year is 4 months.

So for 4 months the rate of interest for the principal amount Rs. 725 remains same as R%.

Total SI = Initial simple interest for 8 months + Added amount simple interest for remaining 4 months + Starting principal amount for remaining 4 months.

Therefore SI = (725 * 8 * R/100 * 12) + (362. 50 * 4 * 2R/100 * 12) + (725 * 4 * R/100 * 12).
You will get the correct answer.

Here P= 725 ( For 8 month).

SI= (725 * 8÷12 * r)/100=550r/100
And after 8 month , P= 362.50 more
And p become 725+ 362.50= 1087.50.

Now, SI would be (1087.50 * 2r * 4÷12)/100 =725r/100 ( as the rate of interest double and count for only 4 months).

We have given,(550r+725r)/100 = 33.50
1275r = 3350.

r = 3350/1275 = 2.62 (which is not in the option).

So, the answer is option E- None of these.

In question there is written After 8 months the rate is twice.

Then, why in the answer this is written the new rate (twice) is only for 4 months.