To find Rate when Principal Interest and Time are given the rules are.
Interest = (Principal × Rate × Time)/100
Rate = (100 × Interest)/(Principal × Time)
Examples to find Rate when Principal, Interest and Time are given:
1.Find Rate, when Principal = $ 3000; Interest = $ 400; Time = 3 years.
Solution:
Principal = $ 3000,
Interest = $ 400,
Time = 3 years.
Rate = (100 × Interest)/(Principal × Time)
= (100 × 400)/(3000 × 3)
= 40000/9000
= 4.44 %
Therefore, Rate = 4.44 %.
2. Find Rate, when Principal = $ 2100; Interest = $ 350; Time = 2 years.
Solution:
Principal = $ 2100,
Interest = $ 350,
Time = 2 years.
Rate = (100 × Interest)/(Principal × Time)
= (100 × 350)/(2100 × 2)
= 35000/4200
= 8.33 %
Therefore, Rate = 8.33 %.
3. Find Rate, when Principal = $ 10000; Interest = $ 800; Time = 5 years.
Solution:
Principal = $ 10000,
Interest = $ 800,
Time = 5 years.
Rate = (100 × Interest)/(Principal × Time)
= (100 × 800)/(10000 × 5)
= 80000/50000
= 1.6 %
Therefore, Rate = 1.6 %.
4. Richard deposits 5400 and got back an amount of 6000 after 2 years. Find Richard's interest rate.
Solution:
Amount deposited by Richard = 5400
He received the amount of money after 2 years = 6000
Simple Interest = 6000 – 5400= 600
Principal = $ 5400
Interest = $ 600,
Time = 2 years.
Rate = (100 × Interest)/(Principal × Time)
= (100 × 600)/(5400 × 2)
= 60000/10800
= 50/9
= 5.555….
= 5.56 %
(Nearest to two decimal place)
Therefore, Rate = 5.56 %.
Word Problems on Simple Interest.
In Simple Interest when the Time is given in Months and Days.
To find Principal when Time Interest and Rate are given.
To find Rate when Principal Interest and Time are given .
To find Time when Principal Interest and Rate are given.
Worksheet on Factors affecting Interest
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