Simple Interest
Math MCQs

Question :    Calculate the amount due if Susan borrowed a sum of $3650 at 4% simple interest for 4 years.

Correct Answer  $4234

Solution & Explanation

Solution

Given,

Principal (P) = $3650

Rate of Simple Interest (SI) = 4%

Time (t) = 4 years

Thus, Amount (A) = ?

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

Thus, here 4% simple interest means, Rate of Simple Interest (SI) is 4% 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) = $3650 × 4% × 4

= $3650 ×⁴/₁₀₀ × 4

= ^{3650 × 4 × 4}/₁₀₀

= ^{14600 × 4}/₁₀₀

= ⁵⁸⁴⁰⁰/₁₀₀

= $584

Thus, Simple Interest = $584

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 = $3650 + $584

= $4234

Thus, Amount to be paid = $4234 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 = $3650

Rate of Simple Interest (SI) or (R) = 4%

And, Time (t) = 4 years

Thus, Amount (A)

= $3650 + ($3650 × 4% × 4)

= $3650 + ($3650 ×⁴/₁₀₀ × 4)

= $3650 + (^{3650 × 4 × 4}/₁₀₀)

= $3650 + (^{14600 × 4}/₁₀₀)

= $3650 + (⁵⁸⁴⁰⁰/₁₀₀)

= $3650 + $584 = $4234

Thus, Amount (A) to be paid = $4234 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 4%

This, means, $4 per $100 per year

∵ For $100, the simple interest for 1 year = $4

∴ For $1, the simple interest for 1 year = ⁴/₁₀₀

∴ For $3650, the simple interest in 1 year

= ⁴/₁₀₀ × 3650

= ^{4 × 3650}/₁₀₀

= ¹⁴⁶⁰⁰/₁₀₀ = $146

Thus, simple interest for 1 year = $146

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $146 × 4 = $584

Thus, Simple Interest (SI) = $584

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3650 + $584

= $4234

Thus, Amount to be paid = $4234 Answer

Similar Questions

(1) Calculate the amount due after 9 years if Joseph borrowed a sum of $5700 at a rate of 8% simple interest.

(2) How much loan did Jennifer borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $6562.5 to clear it?

(3) Calculate the amount due if Joseph borrowed a sum of $3700 at 10% simple interest for 3 years.

(4) Calculate the amount due after 10 years if William borrowed a sum of $5500 at a rate of 2% simple interest.

(5) How much loan did Timothy borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $8880 to clear it?

(6) Find the amount to be paid if Jessica borrowed a sum of $5750 at 10% simple interest for 8 years.

(7) Find the amount to be paid if Patricia borrowed a sum of $5150 at 10% simple interest for 8 years.

(8) Find the amount to be paid if James borrowed a sum of $5000 at 3% simple interest for 8 years.

(9) Find the amount to be paid if Charles borrowed a sum of $5900 at 8% simple interest for 7 years.

(10) What amount will be due after 2 years if David borrowed a sum of $3200 at a 10% simple interest?