Question:
Calculate the amount due after 9 years if Mary borrowed a sum of $5050 at a rate of 9% simple interest.
Correct Answer
$9140.5
Solution And Explanation
Solution
Given,
Principal (P) = $5050
Rate of Simple Interest (SI) = 9%
Time (t) = 9 years
Thus, Amount (A) = ?
The Rate of Interest is always calculated per annum, i.e. per year.
Thus, here 9% simple interest means, Rate of Simple Interest (SI) is 9% 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) = $5050 × 9% × 9
= $5050 ×9/100 × 9
= 5050 × 9 × 9/100
= 45450 × 9/100
= 409050/100
= $4090.5
Thus, Simple Interest = $4090.5
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 = $5050 + $4090.5
= $9140.5
Thus, Amount to be paid = $9140.5 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 = $5050
Rate of Simple Interest (SI) or (R) = 9%
And, Time (t) = 9 years
Thus, Amount (A)
= $5050 + ($5050 × 9% × 9)
= $5050 + ($5050 ×9/100 × 9)
= $5050 + (5050 × 9 × 9/100)
= $5050 + (45450 × 9/100)
= $5050 + (409050/100)
= $5050 + $4090.5 = $9140.5
Thus, Amount (A) to be paid = $9140.5 Answer
Method (3) Unitary Method
Calculation of Amount using Unitary Method
Calculation of Interest using Unitary Method
Here, given Rate of Simple Interest = 9%
This, means, $9 per $100 per year
∵ For $100, the simple interest for 1 year = $9
∴ For $1, the simple interest for 1 year = 9/100
∴ For $5050, the simple interest in 1 year
= 9/100 × 5050
= 9 × 5050/100
= 45450/100 = $454.5
Thus, simple interest for 1 year = $454.5
Therefore, simple interest for 9 years
= Simple interest for 1 year × 9
= $454.5 × 9 = $4090.5
Thus, Simple Interest (SI) = $4090.5
Calculation of Amount
Amount = Principal + Interest
Thus, Amount = $5050 + $4090.5
= $9140.5
Thus, Amount to be paid = $9140.5 Answer
Similar Questions
(1) Michelle had to pay $5395.5 in order to furnish the loan taken 3 years before. If the rate of simple interest was 3% then find the sum borrowed.
(2) Anthony took a loan of $6600 at the rate of 8% simple interest per annum. If he paid an amount of $11880 to clear the loan, then find the time period of the loan.
(3) Calculate the amount due after 10 years if Susan borrowed a sum of $5650 at a rate of 8% simple interest.
(4) Find the amount to be paid if Jessica borrowed a sum of $5750 at 5% simple interest for 7 years.
(5) What amount does Jessica have to pay after 6 years if he takes a loan of $3750 at 3% simple interest?
(6) Sandra took a loan of $6900 at the rate of 10% simple interest per annum. If he paid an amount of $13800 to clear the loan, then find the time period of the loan.
(7) Find the amount to be paid if David borrowed a sum of $5400 at 9% simple interest for 7 years.
(8) Jennifer had to pay $3445 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.
(9) Calculate the amount due after 9 years if Patricia borrowed a sum of $5150 at a rate of 8% simple interest.
(10) What amount does Patricia have to pay after 6 years if he takes a loan of $3150 at 10% simple interest?