Aptitude - Compound Interest - Discussion
In each of the following questions, a question is asked and is followed by three statements. While answering the question, you may or may not require the data provided in all the statements. You have to read the question and the three statements and then decide whether the question can be answered with any one or two of the statements or all the three statements are required to answer the question. The answer number bearing the statements, which can be dispensed with, if any, while answering the question is your answer.
What is the compound interest earned at the end of 3 years? | |
I. | Simple interest earned on that amount at the same rate and for the same period is Rs. 4500. |
II. | The rate of interest is 10 p.c.p.a. |
III. | Compound interest for 3 years is more than the simple interest for that period by Rs. 465. |
I. gives, S.I for 3 years = Rs. 4500.
II. gives, Rate = 10% p.a.
III. gives, (C.I.) - (S.I.) = Rs. 465.
Clearly, using I and III we get C.I. = Rs. (465 + 4500).
Thus, II is redundant.
| Also, from I and II, we get sum = |  |
100 x 4500 |  |
= 15000. |
| 10 x 3 |
Now C.I. on Rs. 15000 at 10% p.a. for 3 years may be obtained.
Thus, III is redundant.
Either II or III is redundant.
because I is used always and II or III are optional.
According to this, the answer should be "any one of the three" (as any one of the statements can be dispensed) which is not given in options.
We can also find the C.I using 2 II and III.
P*{(1+10/100)^3-1}-p*10*3/100=465.
This will give principal amount.
Since rate and time are known, C.I can be calculated.