Simple Interest
Math MCQs

Question :    Calculate the amount due if Michael borrowed a sum of $3300 at 8% simple interest for 4 years.

Correct Answer  $4356

Solution & Explanation

Solution

Given,

Principal (P) = $3300

Rate of Simple Interest (SI) = 8%

Time (t) = 4 years

Thus, Amount (A) = ?

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

Thus, here 8% simple interest means, Rate of Simple Interest (SI) is 8% 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) = $3300 × 8% × 4

= $3300 ×⁸/₁₀₀ × 4

= ^{3300 × 8 × 4}/₁₀₀

= ^{26400 × 4}/₁₀₀

= ¹⁰⁵⁶⁰⁰/₁₀₀

= $1056

Thus, Simple Interest = $1056

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 = $3300 + $1056

= $4356

Thus, Amount to be paid = $4356 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 = $3300

Rate of Simple Interest (SI) or (R) = 8%

And, Time (t) = 4 years

Thus, Amount (A)

= $3300 + ($3300 × 8% × 4)

= $3300 + ($3300 ×⁸/₁₀₀ × 4)

= $3300 + (^{3300 × 8 × 4}/₁₀₀)

= $3300 + (^{26400 × 4}/₁₀₀)

= $3300 + (¹⁰⁵⁶⁰⁰/₁₀₀)

= $3300 + $1056 = $4356

Thus, Amount (A) to be paid = $4356 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 8%

This, means, $8 per $100 per year

∵ For $100, the simple interest for 1 year = $8

∴ For $1, the simple interest for 1 year = ⁸/₁₀₀

∴ For $3300, the simple interest in 1 year

= ⁸/₁₀₀ × 3300

= ^{8 × 3300}/₁₀₀

= ²⁶⁴⁰⁰/₁₀₀ = $264

Thus, simple interest for 1 year = $264

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $264 × 4 = $1056

Thus, Simple Interest (SI) = $1056

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3300 + $1056

= $4356

Thus, Amount to be paid = $4356 Answer

Similar Questions

(1) Find the amount to be paid if Karen borrowed a sum of $5950 at 4% simple interest for 7 years.

(2) Calculate the amount due if Barbara borrowed a sum of $3550 at 10% simple interest for 4 years.

(3) Calculate the amount due after 10 years if Susan borrowed a sum of $5650 at a rate of 4% simple interest.

(4) Find the amount to be paid if Robert borrowed a sum of $5100 at 5% simple interest for 8 years.

(5) Betty took a loan of $6500 at the rate of 8% simple interest per annum. If he paid an amount of $10140 to clear the loan, then find the time period of the loan.

(6) Matthew took a loan of $6400 at the rate of 6% simple interest per annum. If he paid an amount of $9856 to clear the loan, then find the time period of the loan.

(7) How much loan did Joshua borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $7590 to clear it?

(8) Calculate the amount due if William borrowed a sum of $3500 at 7% simple interest for 3 years.

(9) If Jessica borrowed $3750 from a bank at a rate of 3% simple interest per annum then find the amount to be paid after 2 years.

(10) Calculate the amount due if Christopher borrowed a sum of $4000 at 2% simple interest for 3 years.