Aptitude - Simple Interest - Discussion


Reena took a loan of Rs. 1200 with simple interest for as many years as the rate of interest. If she paid Rs. 432 as interest at the end of the loan period, what was the rate of interest?

[A]. 3.6
[B]. 6
[C]. 18
[D]. Cannot be determined
[E]. None of these

Answer: Option B


Let rate = R% and time = R years.

Then, 1200 x R x R = 432

12R2 = 432

R2 = 36

R = 6.

Video Explanation: https://youtu.be/TjjI4iRkzT0

Bhavya Y J said: (Jun 11, 2010)  
While traveling at uniform speed. U read a two digit no. after one hr the number is reversed order. After another hour the number read is same two digit number. What is the average speed?

Ppp said: (Feb 17, 2011)  
Why should we take R for time why should not T or Something other?

Sakshi said: (Mar 6, 2011)  
You are right Ppp.
We can also take x.
according to the question R=T.we can take R=T=x
R= S.I*100/P*T
x to the power square =36; x= 6

Vaani said: (May 7, 2011)  
As many years as the rate of interest so we taken t=r

Sanju said: (May 20, 2011)  
According to ques we can also take x, y, z it is not a matter.

Hasmukh Maniya said: (Jun 13, 2011)  
But Why we took R two times in this Solution..

We can Take Like R=Rate of Interest and T=Time

the Formula is SI=PRT/100

In this Formula if We take 1 year then the ans will be 36 instead of 6.

Plz Give me Proper Solution for my biggest Confusion..As Soon As

Kishan said: (Sep 17, 2011)  
Reena took a loan of Rs. 1200 with simple interest for as many years as the rate of interest.

Please solve the above sentence.

Anil said: (Oct 4, 2011)  
Actually, I am unable to understand what the question is, can anyone please explain me.

Lavs said: (Nov 3, 2011)  
Hai friends
Actually reena took sum of Rs.1200 ie P=1200 and paid simple interest of Rs.432
We are asked to find the rate ie R
It is given that, simple interest for as many years as the rate of interest. this line mean that T=R.
you can asuume R & T to some other variable also ie R=T=x

formulato be used is SI=PRT/100
432=1200*R*R/100 (Here i have used T=R)
43200=1200 R square
Hope understand... Goood night

Jagat said: (Feb 26, 2012)  
I don't understand how we will we take T=R & what is mean of as many year as the rate of interest give actual mean of this sentence.

Tejas said: (May 26, 2012)  
My Answer is 3.6%.
1200*3. 6% = 43.2
Ok now many years means 10 years
So 43.2 * 10 years = 432
Please tell me this is right or wrong, if wrong why?

Banti Biswal said: (Jun 29, 2012)  
Why we take R inplace of T ?

Rajan Kumar said: (Aug 31, 2012)  
Because rate is equal to year they given in question itself.
so we took t=r we can also write like r=t=r all are same in this question.

Gaurav said: (Feb 21, 2013)  
Can anyone solve this, by using the following formula,


where, S.I=Simple Interest,
P=Principal Amount.
N= Period of time.
and, R= Rate of Interest.

Mhndr said: (Sep 17, 2013)  
Friend, There you can use,

t = r = x.

Then r=t or x,

t = r or x.

Thus, r^2 or t^2 or x^2. Hope now you understand.

Rajesh said: (Oct 15, 2013)  
Assume 6 as time and rate of interest.

Then 6% of 1200 is 72.

For six years means (72*6) = 432.

Hence our assumption is correct and 6 is the answer.

Arif said: (Oct 30, 2013)  

According to question Reena took a loan of Rs. 1200 with simple interest for as many years as the rate of interest.

It means rate of interest and time duration both are equal.

Patricia Baldimo said: (Jan 16, 2014)  
Why do we have a 100?

Ganeshgoud said: (Mar 7, 2014)  
R = (S.I*100/P*T).
S.I = 432;
P = 1200;
T = R;
R = 432*100/1200*R.
R2 = 36.
R = 6.

Raja said: (Nov 22, 2014)  
Please tell me why we take t=r and what is the meanings of many years?

Chandra Kiran.Baru said: (Dec 31, 2014)  
P = 1200.
I = 432.
Time = r.
Rate = r%.

S.I = ptr\100.
432 = 1200*r*r\100.

R2 = 432\12.
R2 = 36 = 6.

Preethi said: (Jan 7, 2015)  
Why here we take t=r?

Rajasekar said: (Feb 12, 2015)  
How you could take the interest (R) and no of the years (R) both are same constant/Value as R?

Rm Doubt said: (Feb 20, 2015)  
It is not mention in the question that rate of interest and time duration both are equal.

Mahaveer said: (May 17, 2016)  
The answer is D.

Because It is not mentioned in the question that rate of interest and time duration both are equal.

Brizelda said: (Aug 21, 2016)  
What is p?

Swa said: (Oct 10, 2016)  
R = 100 * si/p * t.
R^2 = 100 * 432/1200.
So 36, Here we are not taking T. Simply we took R as square because R = T.

Avana said: (Nov 2, 2016)  
So how about making T = x.
It will reach in a point of,
36 = r * x.
In order to make one as subject take the two latter as square and it will lead into 6.
r = 6,
x = 6,
r * x = 36,
6 * 6 = 36.

Rudragouda said: (Nov 10, 2016)  
Why we need to take R here is there any rule for that? Please tell me.

Geeta said: (Nov 11, 2016)  
Why we take replace of T?

Teja said: (Dec 5, 2016)  
First I too confused each subject has its own style of language. Here in the problem itself said r = t and asked interest so r placed here if they ask time means T-square.

Yousuf Mayuri said: (Dec 26, 2016)  
If Reena took Rs. 1200.

SI = P * R * T/100.

She paid of Rs. 432 at the end of the loan period.
Here, rate of interest is directly proportional to time.
P= 1200
SI= 432
R= ?

Therefore , SI = P * R * T/100.
432= 1200 * R * T=R/100,
432=1200 * R * R/100,
432=1200 * R^2/100,
432= 12 * R^2,
432/12 = R^2,
36 = R^2,

R^ = 36.

Therefore, R = 6 Answer.

Anoms said: (Jan 6, 2017)  
Here in question they have mentioned that "interest is as many years of time of end period" so we have to take R = T.

Rama said: (Mar 10, 2017)  
Why you multiplied R 2 times?

Mukesh said: (Mar 16, 2017)  
How can you say that?

Time (R) = Rate of Interest (R).

It may be different.

Mahesh Babu said: (Jun 19, 2017)  
Here they given simple interest for as many years as the rate of interest.

So time =rate of interest so we take them as y.
They given our principal is Rs.1200,
S.I= P*T*R/100.
Here S.I=R.s 432,
Here Time=rate of interest,
So y=6.
So Rate of interest =6%.

Anusha said: (Sep 5, 2017)  
How we assume Rate (R) & Time (T) are equal values?

Maleeha said: (Nov 16, 2017)  
I can't be understand how t= r? please help me to solve the question with simple method.

Anu said: (Dec 27, 2017)  
Why here rate (R) and time (T) taken as same?

Ashima Singh said: (Dec 28, 2017)  
See the solution is:

Principle is-1200
Rate :
Simple interest:432

Now we have to find Rate,
Now apply rate formula.
R=100/txsimple interest /principle.
R=100/t x 432/1200.

Aditya said: (May 7, 2018)  
In question, it is clearly mentioned that as many years as the rate of interest. Means if the year is 6 then rate will be also 6 if the year is 5 then rate is same 5 so we take R or x for both Rate and Time.

Vaishnavi said: (Jun 1, 2018)  
I understand your explanation, thank you @Mahesh Babu.

Vamsi Reddy said: (Jun 13, 2018)  
100% = 1200,
X*X = 432,
X*X = 36,
X = 6.

Nitish Kumar said: (Jun 16, 2018)  
Why we take r=t ?

Please give an correct explanation of this question.

Moumita said: (Jun 23, 2018)  
I don't understand this, please help me.

Mamta said: (Sep 19, 2018)  
Thanks for explaining this.

Sudhakar said: (Dec 19, 2019)  
@Bhavya Answer is two digits number only why because the first one hr is 34 speed and another hr is also same as the speed 34. So avg is 34 only.

Sivakumar Tadisetti said: (Feb 1, 2020)  
Friends, here `as many years as the rate of interest` means
* If you pay Loan Amount + Interest in 2 years(T) then the interest rate should be 2%(R)
* If you pay Loan Amount + Interest in 3 years(T) then the interest rate should be 3%(R)
* If you pay Loan Amount + Interest in 5 years(T) then the interest rate should be 5%(R) and so on

That's the reason, they took R = T and option wise 6 is satisfying the above criteria.

Because 6%(432) = RS.72 needs to pay per year as interest and for 6 years it will be 6 * 72 = RS.432.

So the rate of interest is 6 and years also 6.

Arafat Shaikh said: (May 2, 2020)  
Thanks for explaining it.

Zahid Hasan said: (Oct 25, 2020)  
I= prn/100,

So r=I * 100/pn, atq r=n=x (let),r=36/x as r=n x2=36, x=6.

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