Question:
Calculate the amount due after 9 years if Robert borrowed a sum of $5100 at a rate of 4% simple interest.
Correct Answer
$6936
Solution And Explanation
Solution
Given,
Principal (P) = $5100
Rate of Simple Interest (SI) = 4%
Time (t) = 9 years
Thus, Amount (A) = ?
The Rate of Interest is always calculated per annum, i.e. per year.
Thus, here 4% simple interest means, Rate of Simple Interest (SI) is 4% per annum.
Method (1) Using Formula
Calculation of Simple Interest
Formula to Calculate Simple Interest
Simple Interest (SI) = Principal × Rate × Time
Thus, Simple Interest (SI) = $5100 × 4% × 9
= $5100 ×4/100 × 9
= 5100 × 4 × 9/100
= 20400 × 9/100
= 183600/100
= $1836
Thus, Simple Interest = $1836
Calculation of Amount
The total money paid to the lender by a borrower is called the Amount.
In other words, sum of priciple and interest is called the Amount.
Formula to Calculate the Amount
Amount = Principal + Interest
Thus, Amount = $5100 + $1836
= $6936
Thus, Amount to be paid = $6936 Answer
Method (2)
Calculation of Amount when Principal, Rate of Simple Interest and Time are given
Calculation of Amount directly using Principal, SI, and Time
Formula to calculate the Amount
Amount (A) = Principal (P) + Principal(P) × Rate of Interest (SI) × Time (t)
⇒ A = P + PRT
Here in the question, P = $5100
Rate of Simple Interest (SI) or (R) = 4%
And, Time (t) = 9 years
Thus, Amount (A)
= $5100 + ($5100 × 4% × 9)
= $5100 + ($5100 ×4/100 × 9)
= $5100 + (5100 × 4 × 9/100)
= $5100 + (20400 × 9/100)
= $5100 + (183600/100)
= $5100 + $1836 = $6936
Thus, Amount (A) to be paid = $6936 Answer
Method (3) Unitary Method
Calculation of Amount using Unitary Method
Calculation of Interest using Unitary Method
Here, given Rate of Simple Interest = 4%
This, means, $4 per $100 per year
∵ For $100, the simple interest for 1 year = $4
∴ For $1, the simple interest for 1 year = 4/100
∴ For $5100, the simple interest in 1 year
= 4/100 × 5100
= 4 × 5100/100
= 20400/100 = $204
Thus, simple interest for 1 year = $204
Therefore, simple interest for 9 years
= Simple interest for 1 year × 9
= $204 × 9 = $1836
Thus, Simple Interest (SI) = $1836
Calculation of Amount
Amount = Principal + Interest
Thus, Amount = $5100 + $1836
= $6936
Thus, Amount to be paid = $6936 Answer
Similar Questions
(1) Find the amount to be paid if Barbara borrowed a sum of $5550 at 10% simple interest for 8 years.
(2) Robert took a loan of $4200 at the rate of 9% simple interest per annum. If he paid an amount of $6846 to clear the loan, then find the time period of the loan.
(3) How much loan did Linda borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $6420 to clear it?
(4) What amount does Mary have to pay after 6 years if he takes a loan of $3050 at 4% simple interest?
(5) Find the amount to be paid if David borrowed a sum of $5400 at 7% simple interest for 7 years.
(6) What amount does Barbara have to pay after 5 years if he takes a loan of $3550 at 9% simple interest?
(7) Matthew had to pay $4830 in order to furnish the loan taken 3 years before. If the rate of simple interest was 5% then find the sum borrowed.
(8) What amount does Susan have to pay after 6 years if he takes a loan of $3650 at 5% simple interest?
(9) In how much time a principal of $3100 will amount to $3720 at a simple interest of 5% per annum?
(10) What amount does Charles have to pay after 5 years if he takes a loan of $3900 at 6% simple interest?