Question:
Calculate the amount due if John borrowed a sum of $3200 at 9% simple interest for 4 years.
Correct Answer
$4352
Solution And Explanation
Solution
Given,
Principal (P) = $3200
Rate of Simple Interest (SI) = 9%
Time (t) = 4 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) = $3200 × 9% × 4
= $3200 ×9/100 × 4
= 3200 × 9 × 4/100
= 28800 × 4/100
= 115200/100
= $1152
Thus, Simple Interest = $1152
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 + $1152
= $4352
Thus, Amount to be paid = $4352 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) = 9%
And, Time (t) = 4 years
Thus, Amount (A)
= $3200 + ($3200 × 9% × 4)
= $3200 + ($3200 ×9/100 × 4)
= $3200 + (3200 × 9 × 4/100)
= $3200 + (28800 × 4/100)
= $3200 + (115200/100)
= $3200 + $1152 = $4352
Thus, Amount (A) to be paid = $4352 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 $3200, the simple interest in 1 year
= 9/100 × 3200
= 9 × 3200/100
= 28800/100 = $288
Thus, simple interest for 1 year = $288
Therefore, simple interest for 4 years
= Simple interest for 1 year × 4
= $288 × 4 = $1152
Thus, Simple Interest (SI) = $1152
Calculation of Amount
Amount = Principal + Interest
Thus, Amount = $3200 + $1152
= $4352
Thus, Amount to be paid = $4352 Answer
Similar Questions
(1) In how much time a principal of $3100 will amount to $3410 at a simple interest of 2% per annum?
(2) Daniel had to pay $4715 in order to furnish the loan taken 3 years before. If the rate of simple interest was 5% then find the sum borrowed.
(3) How much loan did Brian borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $7920 to clear it?
(4) What amount does Linda have to pay after 6 years if he takes a loan of $3350 at 9% simple interest?
(5) If Susan borrowed $3650 from a bank at a rate of 2% simple interest per annum then find the amount to be paid after 2 years.
(6) What amount will be due after 2 years if Anthony borrowed a sum of $3650 at a 8% simple interest?
(7) Calculate the amount due after 9 years if Charles borrowed a sum of $5900 at a rate of 10% simple interest.
(8) What amount will be due after 2 years if Charles borrowed a sum of $3450 at a 5% simple interest?
(9) Joshua had to pay $5488 in order to furnish the loan taken 3 years before. If the rate of simple interest was 4% then find the sum borrowed.
(10) Mary had to pay $3507.5 in order to furnish the loan taken 3 years before. If the rate of simple interest was 5% then find the sum borrowed.