Simple Interest
Math MCQs

Question :    Calculate the amount due if Barbara borrowed a sum of $3550 at 4% simple interest for 3 years.

Correct Answer  $3976

Solution & Explanation

Solution

Given,

Principal (P) = $3550

Rate of Simple Interest (SI) = 4%

Time (t) = 3 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) = $3550 × 4% × 3

= $3550 ×⁴/₁₀₀ × 3

= ^{3550 × 4 × 3}/₁₀₀

= ^{14200 × 3}/₁₀₀

= ⁴²⁶⁰⁰/₁₀₀

= $426

Thus, Simple Interest = $426

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 + $426

= $3976

Thus, Amount to be paid = $3976 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) = 4%

And, Time (t) = 3 years

Thus, Amount (A)

= $3550 + ($3550 × 4% × 3)

= $3550 + ($3550 ×⁴/₁₀₀ × 3)

= $3550 + (^{3550 × 4 × 3}/₁₀₀)

= $3550 + (^{14200 × 3}/₁₀₀)

= $3550 + (⁴²⁶⁰⁰/₁₀₀)

= $3550 + $426 = $3976

Thus, Amount (A) to be paid = $3976 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 $3550, the simple interest in 1 year

= ⁴/₁₀₀ × 3550

= ^{4 × 3550}/₁₀₀

= ¹⁴²⁰⁰/₁₀₀ = $142

Thus, simple interest for 1 year = $142

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $142 × 3 = $426

Thus, Simple Interest (SI) = $426

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3550 + $426

= $3976

Thus, Amount to be paid = $3976 Answer

Similar Questions

(1) Find the amount to be paid if Thomas borrowed a sum of $5800 at 5% simple interest for 7 years.

(2) How much loan did Robert borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $6375 to clear it?

(3) What amount does Thomas have to pay after 6 years if he takes a loan of $3800 at 6% simple interest?

(4) Calculate the amount due after 9 years if Christopher borrowed a sum of $6000 at a rate of 2% simple interest.

(5) How much loan did Kenneth borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $7700 to clear it?

(6) What amount will be due after 2 years if John borrowed a sum of $3100 at a 9% simple interest?

(7) Calculate the amount due after 10 years if James borrowed a sum of $5000 at a rate of 8% simple interest.

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

(9) Calculate the amount due if Sarah borrowed a sum of $3850 at 7% simple interest for 4 years.

(10) Calculate the amount due if Joseph borrowed a sum of $3700 at 10% simple interest for 4 years.