Question:
Calculate the amount due if John borrowed a sum of $3200 at 5% simple interest for 3 years.
Correct Answer
$3680
Solution And Explanation
Solution
Given,
Principal (P) = $3200
Rate of Simple Interest (SI) = 5%
Time (t) = 3 years
Thus, Amount (A) = ?
The Rate of Interest is always calculated per annum, i.e. per year.
Thus, here 5% simple interest means, Rate of Simple Interest (SI) is 5% 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) = $3200 × 5% × 3
= $3200 ×5/100 × 3
= 3200 × 5 × 3/100
= 16000 × 3/100
= 48000/100
= $480
Thus, Simple Interest = $480
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 = $3200 + $480
= $3680
Thus, Amount to be paid = $3680 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 = $3200
Rate of Simple Interest (SI) or (R) = 5%
And, Time (t) = 3 years
Thus, Amount (A)
= $3200 + ($3200 × 5% × 3)
= $3200 + ($3200 ×5/100 × 3)
= $3200 + (3200 × 5 × 3/100)
= $3200 + (16000 × 3/100)
= $3200 + (48000/100)
= $3200 + $480 = $3680
Thus, Amount (A) to be paid = $3680 Answer
Method (3) Unitary Method
Calculation of Amount using Unitary Method
Calculation of Interest using Unitary Method
Here, given Rate of Simple Interest = 5%
This, means, $5 per $100 per year
∵ For $100, the simple interest for 1 year = $5
∴ For $1, the simple interest for 1 year = 5/100
∴ For $3200, the simple interest in 1 year
= 5/100 × 3200
= 5 × 3200/100
= 16000/100 = $160
Thus, simple interest for 1 year = $160
Therefore, simple interest for 3 years
= Simple interest for 1 year × 3
= $160 × 3 = $480
Thus, Simple Interest (SI) = $480
Calculation of Amount
Amount = Principal + Interest
Thus, Amount = $3200 + $480
= $3680
Thus, Amount to be paid = $3680 Answer
Similar Questions
(1) How much loan did Laura borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $9027.5 to clear it?
(2) Betty took a loan of $6500 at the rate of 8% simple interest per annum. If he paid an amount of $10660 to clear the loan, then find the time period of the loan.
(3) Calculate the amount due after 10 years if Richard borrowed a sum of $5600 at a rate of 8% simple interest.
(4) How much loan did Donna borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $8220 to clear it?
(5) What amount does David have to pay after 5 years if he takes a loan of $3400 at 6% simple interest?
(6) Calculate the amount due after 10 years if Elizabeth borrowed a sum of $5450 at a rate of 3% simple interest.
(7) What amount does Karen have to pay after 6 years if he takes a loan of $3950 at 8% simple interest?
(8) What amount will be due after 2 years if Paul borrowed a sum of $3850 at a 5% simple interest?
(9) Donald took a loan of $7000 at the rate of 7% simple interest per annum. If he paid an amount of $10920 to clear the loan, then find the time period of the loan.
(10) Calculate the amount due if Jennifer borrowed a sum of $3250 at 8% simple interest for 4 years.