Simple Interest
Math MCQs

Question :    Find the amount to be paid if Christopher borrowed a sum of $6000 at 8% simple interest for 7 years.

Correct Answer  $9360

Solution & Explanation

Solution

Given,

Principal (P) = $6000

Rate of Simple Interest (SI) = 8%

Time (t) = 7 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) = $6000 × 8% × 7

= $6000 ×⁸/₁₀₀ × 7

= ^{6000 × 8 × 7}/₁₀₀

= ^{48000 × 7}/₁₀₀

= ³³⁶⁰⁰⁰/₁₀₀

= $3360

Thus, Simple Interest = $3360

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 = $6000 + $3360

= $9360

Thus, Amount to be paid = $9360 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 = $6000

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

And, Time (t) = 7 years

Thus, Amount (A)

= $6000 + ($6000 × 8% × 7)

= $6000 + ($6000 ×⁸/₁₀₀ × 7)

= $6000 + (^{6000 × 8 × 7}/₁₀₀)

= $6000 + (^{48000 × 7}/₁₀₀)

= $6000 + (³³⁶⁰⁰⁰/₁₀₀)

= $6000 + $3360 = $9360

Thus, Amount (A) to be paid = $9360 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 $6000, the simple interest in 1 year

= ⁸/₁₀₀ × 6000

= ^{8 × 6000}/₁₀₀

= ⁴⁸⁰⁰⁰/₁₀₀ = $480

Thus, simple interest for 1 year = $480

Therefore, simple interest for 7 years

= Simple interest for 1 year × 7

= $480 × 7 = $3360

Thus, Simple Interest (SI) = $3360

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $6000 + $3360

= $9360

Thus, Amount to be paid = $9360 Answer

Similar Questions

(1) How much loan did Matthew borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $7440 to clear it?

(2) What amount will be due after 2 years if Michael borrowed a sum of $3150 at a 9% simple interest?

(3) Find the amount to be paid if David borrowed a sum of $5400 at 10% simple interest for 8 years.

(4) Calculate the amount due after 10 years if Charles borrowed a sum of $5900 at a rate of 4% simple interest.

(5) Calculate the amount due after 10 years if Michael borrowed a sum of $5300 at a rate of 9% simple interest.

(6) James had to pay $3360 in order to furnish the loan taken 3 years before. If the rate of simple interest was 4% then find the sum borrowed.

(7) How much loan did Donna borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $7535 to clear it?

(8) Calculate the amount due if Charles borrowed a sum of $3900 at 7% simple interest for 3 years.

(9) Calculate the amount due if Richard borrowed a sum of $3600 at 7% simple interest for 4 years.

(10) What amount does Jessica have to pay after 5 years if he takes a loan of $3750 at 5% simple interest?