Simple Interest
Math MCQs

Question :    Calculate the amount due if Michael borrowed a sum of $3300 at 10% simple interest for 4 years.

Correct Answer  $4620

Solution & Explanation

Solution

Given,

Principal (P) = $3300

Rate of Simple Interest (SI) = 10%

Time (t) = 4 years

Thus, Amount (A) = ?

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

Thus, here 10% simple interest means, Rate of Simple Interest (SI) is 10% 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) = $3300 × 10% × 4

= $3300 ×¹⁰/₁₀₀ × 4

= ^{3300 × 10 × 4}/₁₀₀

= ^{33000 × 4}/₁₀₀

= ¹³²⁰⁰⁰/₁₀₀

= $1320

Thus, Simple Interest = $1320

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 = $3300 + $1320

= $4620

Thus, Amount to be paid = $4620 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 = $3300

Rate of Simple Interest (SI) or (R) = 10%

And, Time (t) = 4 years

Thus, Amount (A)

= $3300 + ($3300 × 10% × 4)

= $3300 + ($3300 ×¹⁰/₁₀₀ × 4)

= $3300 + (^{3300 × 10 × 4}/₁₀₀)

= $3300 + (^{33000 × 4}/₁₀₀)

= $3300 + (¹³²⁰⁰⁰/₁₀₀)

= $3300 + $1320 = $4620

Thus, Amount (A) to be paid = $4620 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 10%

This, means, $10 per $100 per year

∵ For $100, the simple interest for 1 year = $10

∴ For $1, the simple interest for 1 year = ¹⁰/₁₀₀

∴ For $3300, the simple interest in 1 year

= ¹⁰/₁₀₀ × 3300

= ^{10 × 3300}/₁₀₀

= ³³⁰⁰⁰/₁₀₀ = $330

Thus, simple interest for 1 year = $330

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $330 × 4 = $1320

Thus, Simple Interest (SI) = $1320

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3300 + $1320

= $4620

Thus, Amount to be paid = $4620 Answer

Similar Questions

(1) Calculate the amount due if Elizabeth borrowed a sum of $3450 at 7% simple interest for 3 years.

(2) What amount does Sarah have to pay after 6 years if he takes a loan of $3850 at 10% simple interest?

(3) What amount will be due after 2 years if Joseph borrowed a sum of $3350 at a 8% simple interest?

(4) Richard took a loan of $5200 at the rate of 10% simple interest per annum. If he paid an amount of $10400 to clear the loan, then find the time period of the loan.

(5) If Kenneth paid $5600 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(6) What amount does John have to pay after 6 years if he takes a loan of $3200 at 8% simple interest?

(7) Linda took a loan of $4700 at the rate of 7% simple interest per annum. If he paid an amount of $6674 to clear the loan, then find the time period of the loan.

(8) Calculate the amount due after 9 years if Patricia borrowed a sum of $5150 at a rate of 8% simple interest.

(9) Calculate the amount due after 10 years if Susan borrowed a sum of $5650 at a rate of 6% simple interest.

(10) Christopher took a loan of $6000 at the rate of 7% simple interest per annum. If he paid an amount of $9780 to clear the loan, then find the time period of the loan.