# Simple and Compound Interest Problems with Shortcut Methods - Lesson 2

Friends, this is the continuation of my previous post on Simple and Compound Interest Problems with Shortcut methods. Please read that post from here before reading this. Happy Reading :)

P.S : Sorry for the bad handwriting :P

Practice Problem 7 : In what time will Rs. 350 amount to Rs. 420 at 5% per annum ?

Solution :

Simple Interest = Amount - Principal  = 420 - 350  = Rs. 70

=> Time = (70 x 100) / (350 x 5) = 4 years

Practice Problem 8 : If the simple interest on Rs. 750 for 3 months is Rs. 22.50, what is the rate of interest percent per annum ?

Solution :

Here P = Rs. 750
Time = 3 months = 1/4 year

and S. I = Rs. 22.50

=> Rate of Interest Percent per annum  = (S. I x 100) / (P x T) = (22.50 x 100) /  (750 x (1/4))

= 12%

Practice Problem 9 : The Simple Interest on certain sum of money for 3 years at 4% is Rs. 303.60. Find the compound interest on the same sum for the same period at the same rate ?

Solution :

S. I = Rs. 303.60,  R = 4%,  t  =  3 years
P = (303.60 x 100) / (4 x 3)  = Rs. 2530
Practice Problem 10 : A sum of money put out at compound interest amounts in one year to Rs. 4050 and in three years to Rs. 4723.92. Find the original sum and the rate of interest ?

Solution :
Putting the value of R in equation (2), we get
Practice Problem 11 : Calculate the compound interest on Rs. 10000 for 3 years at 4% per annum.

Solution :

Compound Interest
Practice Problem 12 : What will be the amount of Rs. 51200 for 3 years at 6 1/4% per annum at compound interest ?

Solution :

Practice Problem 13 : What will be the compound interest on Rs. 15625 for 2 1/2 years at 4% per annum ?

Solution :

Practice Problem 14 : If a person saves Rs. 200 at the end of each year and lends this savings at 5% compound interest, how much will it worth at the end of 3 years ?

Solution :

Practice Problem 15 : If a certain sum of money invested at compound interest amounts to Rs. 2420 in 2 years and to Rs. 2662 in 3 years, what is the principal ?

Solution :

Practice Problem 16 : If the amount of a certain sum at compound interest becomes 2 1/4 times of the principal in 2 years, what is the rate of interest ?

Solution :

That's all for now friends. In our next lesson we shall work with more problems with higher difficulty levels. Happy Reading :)