Aptitude - Simple Interest - Discussion
Discussion Forum : Simple Interest - General Questions (Q.No. 11)
11.
A sum of money amounts to Rs. 9800 after 5 years and Rs. 12005 after 8 years at the same rate of simple interest. The rate of interest per annum is:
Answer: Option
Explanation:
S.I. for 3 years = Rs. (12005 - 9800) = Rs. 2205.
| S.I. for 5 years = Rs. |  |
2205 | x 5 |  |
= Rs. 3675 |
| 3 |
Principal = Rs. (9800 - 3675) = Rs. 6125.
| Hence, rate = | |
100 x 3675 | % |
= 12% |
| 6125 x 5 |
Video Explanation: https://youtu.be/UYwiBCRN39s
Discussion:
68 comments Page 6 of 7.
Kasinath @Hyd said:
1 decade ago
Amount = P+I for 5 years = 9800 --- Eq(1).
Amount = P+I for 8 years =12005 -- Eq(2).
Eq(2)-Eq(1) => Amount = 735 for 3yrs.
Amount = P+I per year = 2205/3 = 735.
Therefore data is Inadequate to find Rate of interest.
But why Everyone took 9800 as SI sometimes and as principal sometimes. please help
Amount = P+I for 8 years =12005 -- Eq(2).
Eq(2)-Eq(1) => Amount = 735 for 3yrs.
Amount = P+I per year = 2205/3 = 735.
Therefore data is Inadequate to find Rate of interest.
But why Everyone took 9800 as SI sometimes and as principal sometimes. please help
Dinesh said:
1 decade ago
Why we didn't calculate for 8 yrs?
Dharshan said:
1 decade ago
SI For 3 years = 12500-9800 = 2205.
SI For 1 year = 2205/3 = 735.
So, SI For 5 years = 5*735 = 3675.
Principal for 5 years = 9800-3675 = 6125.
Now calculate rate for 5 years = (3675*100)/(6125*5) = 12%.
SI For 1 year = 2205/3 = 735.
So, SI For 5 years = 5*735 = 3675.
Principal for 5 years = 9800-3675 = 6125.
Now calculate rate for 5 years = (3675*100)/(6125*5) = 12%.
Zainim said:
1 decade ago
In first step >>> S.I. for 3 years = Rs. (12005 - 9800) = Rs. 2205.
How come it is S.I = 2205?. It should be difference in SI + Principal for 3 years = 2205. How come it is SI alone?
12005 is SI + Principal for 5 years and 9800 is also SI + Principle for 8 years.
How come it is S.I = 2205?. It should be difference in SI + Principal for 3 years = 2205. How come it is SI alone?
12005 is SI + Principal for 5 years and 9800 is also SI + Principle for 8 years.
Sruthi said:
1 decade ago
Why SI for 3yrs and 5yrs are taken instead of 5yrs and 8yrs?
Ravi said:
1 decade ago
No @Bhuvana,
Its not working for all, its depend upon the problem all are our mind calculation.
Its not working for all, its depend upon the problem all are our mind calculation.
Bhuvana said:
1 decade ago
@Mathan.
Whether this formula works in all those similar problems?
Whether this formula works in all those similar problems?
Siva said:
1 decade ago
In first step >>> S.I. for 3 years = Rs. (12005 - 9800) = Rs. 2205.
How come it is S.I = 2205?. It should be difference in SI + Principal for 3 years = 2205. How come it is SI alone?
12005 is SI + Principal for 5yrs and 9800 is also SI + Prncpl for 8 yrs.
please someone explain?
How come it is S.I = 2205?. It should be difference in SI + Principal for 3 years = 2205. How come it is SI alone?
12005 is SI + Principal for 5yrs and 9800 is also SI + Prncpl for 8 yrs.
please someone explain?
Ruku said:
1 decade ago
Thanks madhan, I understand it, thanks lot.
Mathan said:
1 decade ago
For this type of Question, use this formula.
a = 9800 ; b = 12005 ; t1 = 5 yrs ; t2 = 8 yrs
Principal = (at2 - bt1)/(t2-t1)
Rate = ((b-a)x100)/(bt1-at2) %
Hope it works.
a = 9800 ; b = 12005 ; t1 = 5 yrs ; t2 = 8 yrs
Principal = (at2 - bt1)/(t2-t1)
Rate = ((b-a)x100)/(bt1-at2) %
Hope it works.
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