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 2 of 18.

NARENDRA AHIRWAR said:   6 years ago
Given:

First amount = Rs. 815.
Second amount=Rs. 854.

Diff of amount = second amount - first amount.
= 854-815.
= 39.
Now, for 3 years;
You will have to multiply.
=39*3.
=117.
So now principal is;
= 815-117,
p= 698.

Manisha Pal said:   6 years ago
We know,

Amount = Principe + interest.
4 year amount= principle + 4 year interest.
3 year amount = principle + 3 year interest.

Then,
39 = 1 year Interest.
Now to calculate principle or sum.
We have formula that, amount - interest.

4 year amount- 4-year interest
854-4*39 =698.

or 3 year amount - 3-year interest.
815-3*39=698.
(1)

Madhav said:   6 years ago
@All.

Amount = Principe + interest.
4 year amount= principle + 4 year interest.
3 year amount = principle + 3 year interest.

Then
39= 1 year Interest
Now to calculate principle or sum
We have formulae that, amount - interest.
4 year amount- 4-year interest
854-4*39 =698.
or 3 year amount - 3-year interest.
815-3*39=698.

Ismail khan said:   1 decade ago
Amount for three years is 815
so AMOUNT= p + SI
A = p + pin
815= p + 3pi.......... (1)
similerly for 4 years
854 = p +4pi..........(2)
subtracting equation (1) from(2) we get
39 = pi
or
pi =39
put this value of pi in equation (1) we get
815= p+ 3*39
815= p+ 117
815-117=p
p=698

Jedip said:   4 years ago
@All.

Sum of Amount = Principal Amount + Interest.

here given Sum of Amount is,
815 ----> 3 year.
854 ----> 4 year.

854 - 815 = 39 Simple Interest Per year (because we have a question for per year interest)

39 * 3 = 117.

Sum of Amount = Principal Amount + Interest.
815 = P + 117,
P = 815-117,
P = 698.
(11)

Vikram said:   1 decade ago
According to the question,

SI + P = 815 in three years and
SI + P = 854 in four years

so 815 - P = SI and
854 - P = SI
Therefore,

815 - P = (P * 3 * R)/100 and ---- eq 1
854 - P = (P * 4 * R)/100 ---- eq 2
Now,
eq 1 / eq 2 gives

(815 - P)/(854 - P) = 3/4
Solving this eq, we get
P = 698
(1)

Appu said:   1 decade ago
Hai friends,

Principle is the amount borrowed. Here, explain about SI of 3 years and 4 years. Assume P is the principal then, P+854 for 4 years and p+815 for 3yrs.

So here it is necessary to find the SI of one year and subtract it from the 3 year or 4 year.

That is, (815-117) = 698 and 854-156=698.
(2)

Rahul dev singh said:   9 years ago
If certain principal amounts to A1 in T1 year and to A2 in T2 year ,then the sum is given by = A2 .T1--A1.T2
_____________
T2--T1
Now use the formula
= 854 * 3 -- 815 * 4
________________
4--3
= 2562--3260
____________
1
= 698.

Yash said:   6 years ago
A sum of money at simple interest amounts to Rs. 815 in 3 years := P + SI(3 years) = 815
and to Rs. 854 in 4 years := P + SI(4 years) = 854.

p+(p*r*3)/100=815 ------> 1
p+(p*r*4)/100=854 -------> 2
on solving 1 and 2 you get := pr=3900.
put value of pr in eq-1 ,you get := p=698 (answer).
(2)

Madhav said:   4 years ago
Principal amt with SI for 3 yrs = 815 = total sum of money.
Principal amt with SI for 4 yrs = 854 = total sum of money.

So, to find SI for 1 yr = 854-815 = 39,
So, SI for 3 yrs = 39 *3 = 117 or Si for 4 yrs = 39*4 =156,


Total sum for 3yrs = P+SI..815 = P + 117..P= 815 -117 = 698.
(63)


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