Question:
Calculate the amount due if Charles borrowed a sum of $3900 at 3% simple interest for 4 years.
Correct Answer
$4368
Solution And Explanation
Solution
Given,
Principal (P) = $3900
Rate of Simple Interest (SI) = 3%
Time (t) = 4 years
Thus, Amount (A) = ?
The Rate of Interest is always calculated per annum, i.e. per year.
Thus, here 3% simple interest means, Rate of Simple Interest (SI) is 3% 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) = $3900 × 3% × 4
= $3900 ×3/100 × 4
= 3900 × 3 × 4/100
= 11700 × 4/100
= 46800/100
= $468
Thus, Simple Interest = $468
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 = $3900 + $468
= $4368
Thus, Amount to be paid = $4368 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 = $3900
Rate of Simple Interest (SI) or (R) = 3%
And, Time (t) = 4 years
Thus, Amount (A)
= $3900 + ($3900 × 3% × 4)
= $3900 + ($3900 ×3/100 × 4)
= $3900 + (3900 × 3 × 4/100)
= $3900 + (11700 × 4/100)
= $3900 + (46800/100)
= $3900 + $468 = $4368
Thus, Amount (A) to be paid = $4368 Answer
Method (3) Unitary Method
Calculation of Amount using Unitary Method
Calculation of Interest using Unitary Method
Here, given Rate of Simple Interest = 3%
This, means, $3 per $100 per year
∵ For $100, the simple interest for 1 year = $3
∴ For $1, the simple interest for 1 year = 3/100
∴ For $3900, the simple interest in 1 year
= 3/100 × 3900
= 3 × 3900/100
= 11700/100 = $117
Thus, simple interest for 1 year = $117
Therefore, simple interest for 4 years
= Simple interest for 1 year × 4
= $117 × 4 = $468
Thus, Simple Interest (SI) = $468
Calculation of Amount
Amount = Principal + Interest
Thus, Amount = $3900 + $468
= $4368
Thus, Amount to be paid = $4368 Answer
Similar Questions
(1) Calculate the amount due after 9 years if Thomas borrowed a sum of $5800 at a rate of 5% simple interest.
(2) Calculate the amount due after 9 years if Linda borrowed a sum of $5350 at a rate of 2% simple interest.
(3) Calculate the amount due if Patricia borrowed a sum of $3150 at 3% simple interest for 3 years.
(4) What amount does Richard have to pay after 5 years if he takes a loan of $3600 at 5% simple interest?
(5) Mary took a loan of $4100 at the rate of 6% simple interest per annum. If he paid an amount of $6560 to clear the loan, then find the time period of the loan.
(6) Margaret took a loan of $6700 at the rate of 9% simple interest per annum. If he paid an amount of $10318 to clear the loan, then find the time period of the loan.
(7) Find the amount to be paid if Sarah borrowed a sum of $5850 at 2% simple interest for 8 years.
(8) Find the amount to be paid if Christopher borrowed a sum of $6000 at 4% simple interest for 7 years.
(9) Calculate the amount due if David borrowed a sum of $3400 at 7% simple interest for 4 years.
(10) Find the amount to be paid if Robert borrowed a sum of $5100 at 4% simple interest for 7 years.