1. Given Interest or Amount Find P or n or r

2. Recap on simple interest
Amount = Principal + Interest
Where n is in years

3. Solution Given:- Principal(p)=3500, Interest = 1575, rate=9%
Example1: Naveen invested Rs.3500 in a bank with the rate interest of 9% per
annum. After some years he received RS.1575 as an interest. Find the number
of years.
Solution Given:- Principal(p)=3500, Interest = 1575, rate=9%
To Find:- number of years 5 45
315 7
n = 5
Ans:- number of years = 5

4. Example 2: A certain sum of money amounts to Rs 210 as
interest in 2 years at 7 % . Find the principal.
Solution
Given: I= 210 , r=7% , n=2 years.
To Find: Principal(p)
Ans: Principal (P) = 1500

5. Example 3:- Find the rate percent per annum when a principal of Rs
Example 3:- Find the rate percent per annum when a principal of Rs.5,000 earns a S.I. of Rs.1,250 in 1 year. Solution : Given: p= 5,000 n= 1 year I=1250 To Find : Rate (r)
Ans : r = 25%

6. Example 4: Ram invested Rs
Example 4: Ram invested Rs. 5,000 at the rate of 5 % simple interest per annum. He received the amount with simple interest of 500 after some years. Find the number of years. Solution Given P=5000 r=5% , I=500 To Find: Number of year(n)
Ans:- N= 2 years

7. Example5: Sathya deposited Rs.6,000 in a bank and received Rs.7500 at
the end of 5 years. Find the rate of interest
Solution Given:- Principal(p)=6000, Amount(A)=7500, no of years(n)=5
To Find:- rate(r)
Amount = Principal + Interest
Interest = Amount – Principal
= = 1500 5 20 4
r = 5
Ans:- rate of interest = 5%

8. Example 6:- Sita invested Rs
Example 6:- Sita invested Rs. 5,000 at the rate of 5 % simple interest per annum. She received Rs. 5,500 after some years. Find the number of years. Solution Given : A= Rs. 5,500 , p=Rs , r= 5% To Find: Number of year(n) I = A-P I = 5, ,000 I = 500
Ans:- N= 2 years

9. Try these
1. Bhavana invested Rs.25,000 for 6 years and received an amount
of Rs Find the rate of Interest
2. An amounts Rs.15,000 invested at 4 % per annum earns an
Interest of Rs Find the number of years