Simple Interest
Math MCQs

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

Correct Answer  $8940

Solution & Explanation

Solution

Given,

Principal (P) = $6000

Rate of Simple Interest (SI) = 7%

Time (t) = 7 years

Thus, Amount (A) = ?

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

Thus, here 7% simple interest means, Rate of Simple Interest (SI) is 7% 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 × 7% × 7

= $6000 ×⁷/₁₀₀ × 7

= ^{6000 × 7 × 7}/₁₀₀

= ^{42000 × 7}/₁₀₀

= ²⁹⁴⁰⁰⁰/₁₀₀

= $2940

Thus, Simple Interest = $2940

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 + $2940

= $8940

Thus, Amount to be paid = $8940 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) = 7%

And, Time (t) = 7 years

Thus, Amount (A)

= $6000 + ($6000 × 7% × 7)

= $6000 + ($6000 ×⁷/₁₀₀ × 7)

= $6000 + (^{6000 × 7 × 7}/₁₀₀)

= $6000 + (^{42000 × 7}/₁₀₀)

= $6000 + (²⁹⁴⁰⁰⁰/₁₀₀)

= $6000 + $2940 = $8940

Thus, Amount (A) to be paid = $8940 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 7%

This, means, $7 per $100 per year

∵ For $100, the simple interest for 1 year = $7

∴ For $1, the simple interest for 1 year = ⁷/₁₀₀

∴ For $6000, the simple interest in 1 year

= ⁷/₁₀₀ × 6000

= ^{7 × 6000}/₁₀₀

= ⁴²⁰⁰⁰/₁₀₀ = $420

Thus, simple interest for 1 year = $420

Therefore, simple interest for 7 years

= Simple interest for 1 year × 7

= $420 × 7 = $2940

Thus, Simple Interest (SI) = $2940

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $6000 + $2940

= $8940

Thus, Amount to be paid = $8940 Answer

Similar Questions

(1) Calculate the amount due after 9 years if Linda borrowed a sum of $5350 at a rate of 2% simple interest.

(2) Find the amount to be paid if Robert borrowed a sum of $5100 at 6% simple interest for 8 years.

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

(4) How much loan did Matthew borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $7750 to clear it?

(5) Calculate the amount due if David borrowed a sum of $3400 at 10% simple interest for 4 years.

(6) Calculate the amount due after 9 years if Patricia borrowed a sum of $5150 at a rate of 4% simple interest.

(7) Find the amount to be paid if Jessica borrowed a sum of $5750 at 4% simple interest for 7 years.

(8) Calculate the amount due if Mary borrowed a sum of $3050 at 4% simple interest for 3 years.

(9) Calculate the amount due after 9 years if William borrowed a sum of $5500 at a rate of 2% simple interest.

(10) Calculate the amount due if David borrowed a sum of $3400 at 7% simple interest for 3 years.