Simple Interest
Math MCQs

Question :    Calculate the amount due if Barbara borrowed a sum of $3550 at 5% simple interest for 4 years.

Correct Answer  $4260

Solution & Explanation

Solution

Given,

Principal (P) = $3550

Rate of Simple Interest (SI) = 5%

Time (t) = 4 years

Thus, Amount (A) = ?

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

Thus, here 5% simple interest means, Rate of Simple Interest (SI) is 5% 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) = $3550 × 5% × 4

= $3550 ×⁵/₁₀₀ × 4

= ^{3550 × 5 × 4}/₁₀₀

= ^{17750 × 4}/₁₀₀

= ⁷¹⁰⁰⁰/₁₀₀

= $710

Thus, Simple Interest = $710

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 = $3550 + $710

= $4260

Thus, Amount to be paid = $4260 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 = $3550

Rate of Simple Interest (SI) or (R) = 5%

And, Time (t) = 4 years

Thus, Amount (A)

= $3550 + ($3550 × 5% × 4)

= $3550 + ($3550 ×⁵/₁₀₀ × 4)

= $3550 + (^{3550 × 5 × 4}/₁₀₀)

= $3550 + (^{17750 × 4}/₁₀₀)

= $3550 + (⁷¹⁰⁰⁰/₁₀₀)

= $3550 + $710 = $4260

Thus, Amount (A) to be paid = $4260 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 5%

This, means, $5 per $100 per year

∵ For $100, the simple interest for 1 year = $5

∴ For $1, the simple interest for 1 year = ⁵/₁₀₀

∴ For $3550, the simple interest in 1 year

= ⁵/₁₀₀ × 3550

= ^{5 × 3550}/₁₀₀

= ¹⁷⁷⁵⁰/₁₀₀ = $177.5

Thus, simple interest for 1 year = $177.5

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $177.5 × 4 = $710

Thus, Simple Interest (SI) = $710

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3550 + $710

= $4260

Thus, Amount to be paid = $4260 Answer

Similar Questions

(1) Calculate the amount due if Sarah borrowed a sum of $3850 at 10% simple interest for 4 years.

(2) What amount will be due after 2 years if Donald borrowed a sum of $3750 at a 10% simple interest?

(3) Find the amount to be paid if Richard borrowed a sum of $5600 at 9% simple interest for 7 years.

(4) How much loan did Ryan borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $9085 to clear it?

(5) Find the amount to be paid if William borrowed a sum of $5500 at 10% simple interest for 7 years.

(6) Calculate the amount due after 9 years if Michael borrowed a sum of $5300 at a rate of 6% simple interest.

(7) In how much time a principal of $3150 will amount to $3937.5 at a simple interest of 5% per annum?

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

(9) If John paid $3584 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

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