To find Rate when Principal Interest and Time are given



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 %.



Related Links :



Simple Interest.
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  • 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 Simple Interest.




  • 5th Grade Numbers Page

    5th Grade Math Problems

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