Simple Interest
Math MCQs

Question :    Calculate the amount due if John borrowed a sum of $3200 at 9% simple interest for 3 years.

Correct Answer  $4064

Solution & Explanation

Solution

Given,

Principal (P) = $3200

Rate of Simple Interest (SI) = 9%

Time (t) = 3 years

Thus, Amount (A) = ?

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

Thus, here 9% simple interest means, Rate of Simple Interest (SI) is 9% 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) = $3200 × 9% × 3

= $3200 ×⁹/₁₀₀ × 3

= ^{3200 × 9 × 3}/₁₀₀

= ^{28800 × 3}/₁₀₀

= ⁸⁶⁴⁰⁰/₁₀₀

= $864

Thus, Simple Interest = $864

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 = $3200 + $864

= $4064

Thus, Amount to be paid = $4064 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 = $3200

Rate of Simple Interest (SI) or (R) = 9%

And, Time (t) = 3 years

Thus, Amount (A)

= $3200 + ($3200 × 9% × 3)

= $3200 + ($3200 ×⁹/₁₀₀ × 3)

= $3200 + (^{3200 × 9 × 3}/₁₀₀)

= $3200 + (^{28800 × 3}/₁₀₀)

= $3200 + (⁸⁶⁴⁰⁰/₁₀₀)

= $3200 + $864 = $4064

Thus, Amount (A) to be paid = $4064 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 9%

This, means, $9 per $100 per year

∵ For $100, the simple interest for 1 year = $9

∴ For $1, the simple interest for 1 year = ⁹/₁₀₀

∴ For $3200, the simple interest in 1 year

= ⁹/₁₀₀ × 3200

= ^{9 × 3200}/₁₀₀

= ²⁸⁸⁰⁰/₁₀₀ = $288

Thus, simple interest for 1 year = $288

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $288 × 3 = $864

Thus, Simple Interest (SI) = $864

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3200 + $864

= $4064

Thus, Amount to be paid = $4064 Answer

Similar Questions

(1) Mary took a loan of $4100 at the rate of 9% simple interest per annum. If he paid an amount of $6683 to clear the loan, then find the time period of the loan.

(2) Calculate the amount due if Thomas borrowed a sum of $3800 at 7% simple interest for 3 years.

(3) Find the amount to be paid if Barbara borrowed a sum of $5550 at 4% simple interest for 8 years.

(4) Find the amount to be paid if Jennifer borrowed a sum of $5250 at 2% simple interest for 8 years.

(5) What amount will be due after 2 years if David borrowed a sum of $3200 at a 4% simple interest?

(6) What amount does Richard have to pay after 6 years if he takes a loan of $3600 at 8% simple interest?

(7) Calculate the amount due if Michael borrowed a sum of $3300 at 6% simple interest for 3 years.

(8) Jennifer took a loan of $4500 at the rate of 6% simple interest per annum. If he paid an amount of $6120 to clear the loan, then find the time period of the loan.

(9) David took a loan of $4800 at the rate of 10% simple interest per annum. If he paid an amount of $9600 to clear the loan, then find the time period of the loan.

(10) What amount will be due after 2 years if John borrowed a sum of $3100 at a 7% simple interest?