Simple Interest
Math MCQs

Question :    Calculate the amount due after 10 years if Susan borrowed a sum of $5650 at a rate of 2% simple interest.

Correct Answer  $6780

Solution & Explanation

Solution

Given,

Principal (P) = $5650

Rate of Simple Interest (SI) = 2%

Time (t) = 10 years

Thus, Amount (A) = ?

The Rate of Interest is always calculated per annum, i.e. per year.

Thus, here 2% simple interest means, Rate of Simple Interest (SI) is 2% 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) = $5650 × 2% × 10

= $5650 ײ/₁₀₀ × 10

= ^{5650 × 2 × 10}/₁₀₀

= ^{11300 × 10}/₁₀₀

= ¹¹³⁰⁰⁰/₁₀₀

= $1130

Thus, Simple Interest = $1130

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 = $5650 + $1130

= $6780

Thus, Amount to be paid = $6780 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 = $5650

Rate of Simple Interest (SI) or (R) = 2%

And, Time (t) = 10 years

Thus, Amount (A)

= $5650 + ($5650 × 2% × 10)

= $5650 + ($5650 ײ/₁₀₀ × 10)

= $5650 + (^{5650 × 2 × 10}/₁₀₀)

= $5650 + (^{11300 × 10}/₁₀₀)

= $5650 + (¹¹³⁰⁰⁰/₁₀₀)

= $5650 + $1130 = $6780

Thus, Amount (A) to be paid = $6780 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 2%

This, means, $2 per $100 per year

∵ For $100, the simple interest for 1 year = $2

∴ For $1, the simple interest for 1 year = ²/₁₀₀

∴ For $5650, the simple interest in 1 year

= ²/₁₀₀ × 5650

= ^{2 × 5650}/₁₀₀

= ¹¹³⁰⁰/₁₀₀ = $113

Thus, simple interest for 1 year = $113

Therefore, simple interest for 10 years

= Simple interest for 1 year × 10

= $113 × 10 = $1130

Thus, Simple Interest (SI) = $1130

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5650 + $1130

= $6780

Thus, Amount to be paid = $6780 Answer

Similar Questions

(1) In how much time a principal of $3000 will amount to $3180 at a simple interest of 2% per annum?

(2) What amount does Sarah have to pay after 5 years if he takes a loan of $3850 at 6% simple interest?

(3) In how much time a principal of $3000 will amount to $3300 at a simple interest of 5% per annum?

(4) What amount will be due after 2 years if Joshua borrowed a sum of $3950 at a 4% simple interest?

(5) Find the amount to be paid if William borrowed a sum of $5500 at 7% simple interest for 8 years.

(6) Find the amount to be paid if Michael borrowed a sum of $5300 at 5% simple interest for 8 years.

(7) If Joseph paid $4292 to settle his loan which he had taken 4 years before at a simple interest of 4%, then find the loan taken.

(8) Find the amount to be paid if Susan borrowed a sum of $5650 at 3% simple interest for 7 years.

(9) How much loan did Brian borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $9000 to clear it?

(10) In how much time a principal of $3050 will amount to $3507.5 at a simple interest of 3% per annum?