Aptitude - Simple Interest - Discussion

Discussion Forum : Simple Interest - General Questions (Q.No. 1)
1.
A sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 854 in 4 years. The sum is:
Rs. 650
Rs. 690
Rs. 698
Rs. 700
Answer: Option
Explanation:

S.I. for 1 year = Rs. (854 - 815) = Rs. 39.

S.I. for 3 years = Rs.(39 x 3) = Rs. 117.

Principal = Rs. (815 - 117) = Rs. 698.

Discussion:
171 comments Page 4 of 18.

KRISHNA CHAURASIYA said:   5 years ago
S.I. for 1 year = Rs. (854 - 815) = Rs. 39.
S.I. for 3 years = Rs.(39 x 3) = Rs. 117.
Principal = Rs. (815 - 117) = Rs. 698.

And if you want to calculate from 854
then,
SI for 4 year =Rs(39*4)=156,
Principal =Rs (854 - 156)= 698.
(2)

Priyanka said:   1 decade ago
Hi friends.

Here goes the explanation,

SI for 4 years = Rs 854.
SI for 3 years = Rs 815.

{4-3} = 1.

So SI for 1 year can be {854-815}.
= Rs 39.

So the SI for 3 years can be {39*3}.
= 117.

So principal is 815-117.
= RS 698{ANS}.

Priya said:   1 decade ago
@Lavanya and kanna

To get 1 year difference we have to subtract
4year amount-3year amount
this difference amount is the 1 year simple interest..
that's why..
Rs. (854 - 815) = Rs. 39
39 is 1year S.I.

hope it helps you..

Pacy said:   8 years ago
You can use the formula, SI= PRT.

Here, R= (854-815)/815= 0.0475, T= 3 years, & P= 815.
Therefore, SI= 815*0.0475*3= 117.
Final answer= 815-117= 698.

You can replace T= 4 years & P= 854, the answer is same.

Arti said:   6 years ago
S.I For 3rd yr=815.
S.I For 4th yr=815.

Difference for 1yr = 39.
S.I for 3yrs = 39 * 3 = 117
P=815-117 = 698.

Similarly;
S.I for 4yrs = 39 * 4 = 156,
P = 854-156 = 698.

I hope it gets clear to you all.

Nidhi Chouhan said:   8 years ago
Since principal with the interest is given for two consecutive years therefore its easy to get the S.I. Without any formula. You can also subtract from 854 given that you multiply 39 with 4 (years).

Sharmistha Pan said:   7 years ago
@Aall.

It's already given in the question that simple interest in 3 years amounts to 815. Then why did we again multiply 39*3 for taking out the SI for 3 years.

Please clarify me.

ShamInzu said:   1 decade ago
3y---815.
4y---854.
------------
1y---39.

3y---39*3 = 117 or 4y---39*4 = 156.

815-117 = 698 or 854-156 = 698.

So we could subtract by 854 or 815.

All The best. Think smart.

Rohit said:   7 years ago
A mobile worth Rs. 500 can be bought by paying a down payment of Rs.100 and 8 equal instalments of Rs. 50 each. Calculate the rate of interest.

Please, anyone, solve this.

Daniyal Syed said:   3 years ago
We can subtract it from 854 also but since we had calculated for 3 years we subtract it from 815 if you want to subtract from 854 do this.

4 x 39 = 156,
854 - 156 = 698.
(78)


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