Simple Interest
Math MCQs

Question :    Calculate the amount due if David borrowed a sum of $3400 at 8% simple interest for 3 years.

Correct Answer  $4216

Solution & Explanation

Solution

Given,

Principal (P) = $3400

Rate of Simple Interest (SI) = 8%

Time (t) = 3 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) = $3400 × 8% × 3

= $3400 ×⁸/₁₀₀ × 3

= ^{3400 × 8 × 3}/₁₀₀

= ^{27200 × 3}/₁₀₀

= ⁸¹⁶⁰⁰/₁₀₀

= $816

Thus, Simple Interest = $816

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 = $3400 + $816

= $4216

Thus, Amount to be paid = $4216 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 = $3400

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

And, Time (t) = 3 years

Thus, Amount (A)

= $3400 + ($3400 × 8% × 3)

= $3400 + ($3400 ×⁸/₁₀₀ × 3)

= $3400 + (^{3400 × 8 × 3}/₁₀₀)

= $3400 + (^{27200 × 3}/₁₀₀)

= $3400 + (⁸¹⁶⁰⁰/₁₀₀)

= $3400 + $816 = $4216

Thus, Amount (A) to be paid = $4216 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 $3400, the simple interest in 1 year

= ⁸/₁₀₀ × 3400

= ^{8 × 3400}/₁₀₀

= ²⁷²⁰⁰/₁₀₀ = $272

Thus, simple interest for 1 year = $272

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $272 × 3 = $816

Thus, Simple Interest (SI) = $816

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3400 + $816

= $4216

Thus, Amount to be paid = $4216 Answer

Similar Questions

(1) What amount will be due after 2 years if Matthew borrowed a sum of $3600 at a 10% simple interest?

(2) Calculate the amount due if John borrowed a sum of $3200 at 5% simple interest for 3 years.

(3) What amount will be due after 2 years if Kenneth borrowed a sum of $4000 at a 6% simple interest?

(4) Find the amount to be paid if Mary borrowed a sum of $5050 at 4% simple interest for 7 years.

(5) Charles took a loan of $5800 at the rate of 7% simple interest per annum. If he paid an amount of $8642 to clear the loan, then find the time period of the loan.

(6) Sarah had to pay $4427.5 in order to furnish the loan taken 3 years before. If the rate of simple interest was 5% then find the sum borrowed.

(7) What amount does Patricia have to pay after 5 years if he takes a loan of $3150 at 3% simple interest?

(8) Find the amount to be paid if Sarah borrowed a sum of $5850 at 9% simple interest for 8 years.

(9) Nancy had to pay $4399 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.

(10) What amount will be due after 2 years if Anthony borrowed a sum of $3650 at a 4% simple interest?