Aptitude - Simple Interest - Discussion

@All.

Here is the explanation for why you are taking 5 years and not 8 years.

5 years calculation and 8years calculation both the values are same.
S. I for 3 years 12005-9800=2205.
S. I for 1 year= 2205/3=735.
S. I for 5 years=735*5=3675.
S. I for 8 years=735*8=5880
P for 5 years = total amount - s.I => 9800 - 3675 = 6125.
R = si * 100/(p*t)
= 3675 * 100/(6125*5)
= 12%.
P for 8years = 12005 - 5880 = 6125.
R= 5880 * 100/(6125*8),
= 12%.
5years and 8years rate of interest is same.
So take 5 years or 8 years we get the same rate of interest.

Step 1 : Earned simple interest in last 3 year = 12005 - 9800 = 2205.
Step 2 : Earned interest per year = 2205 ÷ 3 = 735.
Step 3 : Since Simple Interest earned per year is 735 hence the sum of Simple Interest for initial 5 years will be;
735 x 5 = 3675.
Step 4: So the Principle amount will be 9800 - 3675 = 6125.
Step 5 : Now use S.I. formula for calculating R%.

How come the difference between 12005 and 98000 is S.I?

I think it should be an Amount where P and I is included. Someone, please help me to get it.

@Harsha.

Because we found 2205 for 3 years and now we find it for 5 years.

Why we should divide 2205 with 3 & multiply with 5? Please explain this step.

Please anyone explain it for me.

@Vipul.

2205=9800*3*R/100.

This wouldn't work as the interest is always calculated on the original principal amount which in this case is 6125.

@Annu.

The Simple Interest remains same whether it is for 1 year or 5 years.

In question, it is clearly mentioned that we need to fine rate of interest per annum that is for 1 year but we had find rate of interest for 5 yrs, is it correct.

Kindly explain.

Why do we take 3 year as SI not as amount? Please explain to me.