Question:
Calculate the amount due if Karen borrowed a sum of $3950 at 7% simple interest for 3 years.
Correct Answer
$4779.5
Solution And Explanation
Solution
Given,
Principal (P) = $3950
Rate of Simple Interest (SI) = 7%
Time (t) = 3 years
Thus, Amount (A) = ?
The Rate of Interest is always calculated per annum, i.e. per year.
Thus, here 7% simple interest means, Rate of Simple Interest (SI) is 7% 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) = $3950 × 7% × 3
= $3950 ×7/100 × 3
= 3950 × 7 × 3/100
= 27650 × 3/100
= 82950/100
= $829.5
Thus, Simple Interest = $829.5
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 = $3950 + $829.5
= $4779.5
Thus, Amount to be paid = $4779.5 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 = $3950
Rate of Simple Interest (SI) or (R) = 7%
And, Time (t) = 3 years
Thus, Amount (A)
= $3950 + ($3950 × 7% × 3)
= $3950 + ($3950 ×7/100 × 3)
= $3950 + (3950 × 7 × 3/100)
= $3950 + (27650 × 3/100)
= $3950 + (82950/100)
= $3950 + $829.5 = $4779.5
Thus, Amount (A) to be paid = $4779.5 Answer
Method (3) Unitary Method
Calculation of Amount using Unitary Method
Calculation of Interest using Unitary Method
Here, given Rate of Simple Interest = 7%
This, means, $7 per $100 per year
∵ For $100, the simple interest for 1 year = $7
∴ For $1, the simple interest for 1 year = 7/100
∴ For $3950, the simple interest in 1 year
= 7/100 × 3950
= 7 × 3950/100
= 27650/100 = $276.5
Thus, simple interest for 1 year = $276.5
Therefore, simple interest for 3 years
= Simple interest for 1 year × 3
= $276.5 × 3 = $829.5
Thus, Simple Interest (SI) = $829.5
Calculation of Amount
Amount = Principal + Interest
Thus, Amount = $3950 + $829.5
= $4779.5
Thus, Amount to be paid = $4779.5 Answer
Similar Questions
(1) Calculate the amount due after 10 years if Barbara borrowed a sum of $5550 at a rate of 5% simple interest.
(2) Calculate the amount due after 9 years if Jessica borrowed a sum of $5750 at a rate of 6% simple interest.
(3) Calculate the amount due if David borrowed a sum of $3400 at 3% simple interest for 4 years.
(4) What amount does Susan have to pay after 6 years if he takes a loan of $3650 at 8% simple interest?
(5) Jessica took a loan of $5500 at the rate of 9% simple interest per annum. If he paid an amount of $9955 to clear the loan, then find the time period of the loan.
(6) What amount does William have to pay after 5 years if he takes a loan of $3500 at 6% simple interest?
(7) Find the amount to be paid if Mary borrowed a sum of $5050 at 10% simple interest for 8 years.
(8) In how much time a principal of $3000 will amount to $3600 at a simple interest of 5% per annum?
(9) If Richard paid $4176 to settle his loan which he had taken 4 years before at a simple interest of 4%, then find the loan taken.
(10) Find the amount to be paid if Linda borrowed a sum of $5350 at 8% simple interest for 8 years.