# Aptitude - Compound Interest - Discussion

Discussion Forum : Compound Interest - General Questions (Q.No. 7)
7.
At what rate of compound interest per annum will a sum of Rs. 1200 become Rs. 1348.32 in 2 years?
6%
6.5%
7%
7.5%
Explanation:

Let the rate be R% p.a.

 Then, 1200 x 1 + R 2 = 1348.32 100

 1 + R 2 = 134832 = 11236 100 120000 10000

 1 + R 2 = 106 2 100 100

 1 + R = 106 100 100

R = 6%

Discussion:
40 comments Page 1 of 4.

Daba said:   2 years ago
Very good, Thanks all for explaining.
(1)

Etsub said:   2 years ago
I can't understand it. Please explain me to get it.

Chimi said:   3 years ago
When 134832/12 = 11236.
120000/12 = 10000.
(3)

Kaushal said:   4 years ago
How to do this problem without applying formula?
(1)

Sanjeev said:   4 years ago
@Praveen.

It's logically.

Vaibhav said:   5 years ago
How come 11236?

Saikat Ghosh said:   6 years ago

The shortcut method to find the Square root of 11236 is:

1*1=1,
2*2=4,
3*3=9,
4*4=16,
5*5=25, 6*6=36, 7*7=49, 8*8=64, 9*9=64, 10*10=100, 11*11=121, 12*12=144..

At first, see the last no i.e 6.
So 6 can be found either in 4 square or in 6 square.
Now, look at the first three numbers i.e. 112 which is near to square 10 as the square root of 11 will be more.

So 10*(10+1)=110.
Now see that 112<110.
So 6 square will be taken. Therefore square root of 11236 is 106.
(1)

Suraj said:   6 years ago
What is the answer, if 9 months is given here instead of 2 years?

Aarav said:   6 years ago
Give shortcut to get the answer clearly.

Praveena said:   6 years ago
1+R/100=106/100.
R/100=106/100-1,
R/100=106-100/100,
R/100=6/100,
100R=600,
R=6.
(5)