Question:
Calculate the amount due if Charles borrowed a sum of $3900 at 3% simple interest for 3 years.
Correct Answer
$4251
Solution And Explanation
Solution
Given,
Principal (P) = $3900
Rate of Simple Interest (SI) = 3%
Time (t) = 3 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% × 3
= $3900 ×3/100 × 3
= 3900 × 3 × 3/100
= 11700 × 3/100
= 35100/100
= $351
Thus, Simple Interest = $351
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 + $351
= $4251
Thus, Amount to be paid = $4251 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) = 3 years
Thus, Amount (A)
= $3900 + ($3900 × 3% × 3)
= $3900 + ($3900 ×3/100 × 3)
= $3900 + (3900 × 3 × 3/100)
= $3900 + (11700 × 3/100)
= $3900 + (35100/100)
= $3900 + $351 = $4251
Thus, Amount (A) to be paid = $4251 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 3 years
= Simple interest for 1 year × 3
= $117 × 3 = $351
Thus, Simple Interest (SI) = $351
Calculation of Amount
Amount = Principal + Interest
Thus, Amount = $3900 + $351
= $4251
Thus, Amount to be paid = $4251 Answer
Similar Questions
(1) Jessica took a loan of $5500 at the rate of 10% simple interest per annum. If he paid an amount of $11000 to clear the loan, then find the time period of the loan.
(2) Calculate the amount due if Barbara borrowed a sum of $3550 at 5% simple interest for 3 years.
(3) John took a loan of $4400 at the rate of 8% simple interest per annum. If he paid an amount of $7568 to clear the loan, then find the time period of the loan.
(4) Thomas took a loan of $5600 at the rate of 6% simple interest per annum. If he paid an amount of $7952 to clear the loan, then find the time period of the loan.
(5) What amount does John have to pay after 6 years if he takes a loan of $3200 at 3% simple interest?
(6) Margaret took a loan of $6700 at the rate of 6% simple interest per annum. If he paid an amount of $10318 to clear the loan, then find the time period of the loan.
(7) How much loan did Sandra borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $8062.5 to clear it?
(8) Find the amount to be paid if James borrowed a sum of $5000 at 2% simple interest for 7 years.
(9) Michael took a loan of $4600 at the rate of 8% simple interest per annum. If he paid an amount of $7912 to clear the loan, then find the time period of the loan.
(10) Christopher had to pay $4240 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.