Simple Interest
Math MCQs

Question :    Calculate the amount due if Charles borrowed a sum of $3900 at 6% simple interest for 4 years.

Correct Answer  $4836

Solution & Explanation

Solution

Given,

Principal (P) = $3900

Rate of Simple Interest (SI) = 6%

Time (t) = 4 years

Thus, Amount (A) = ?

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

Thus, here 6% simple interest means, Rate of Simple Interest (SI) is 6% 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) = $3900 × 6% × 4

= $3900 ×⁶/₁₀₀ × 4

= ^{3900 × 6 × 4}/₁₀₀

= ^{23400 × 4}/₁₀₀

= ⁹³⁶⁰⁰/₁₀₀

= $936

Thus, Simple Interest = $936

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 = $3900 + $936

= $4836

Thus, Amount to be paid = $4836 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 = $3900

Rate of Simple Interest (SI) or (R) = 6%

And, Time (t) = 4 years

Thus, Amount (A)

= $3900 + ($3900 × 6% × 4)

= $3900 + ($3900 ×⁶/₁₀₀ × 4)

= $3900 + (^{3900 × 6 × 4}/₁₀₀)

= $3900 + (^{23400 × 4}/₁₀₀)

= $3900 + (⁹³⁶⁰⁰/₁₀₀)

= $3900 + $936 = $4836

Thus, Amount (A) to be paid = $4836 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 6%

This, means, $6 per $100 per year

∵ For $100, the simple interest for 1 year = $6

∴ For $1, the simple interest for 1 year = ⁶/₁₀₀

∴ For $3900, the simple interest in 1 year

= ⁶/₁₀₀ × 3900

= ^{6 × 3900}/₁₀₀

= ²³⁴⁰⁰/₁₀₀ = $234

Thus, simple interest for 1 year = $234

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $234 × 4 = $936

Thus, Simple Interest (SI) = $936

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3900 + $936

= $4836

Thus, Amount to be paid = $4836 Answer

Similar Questions

(1) Richard took a loan of $5200 at the rate of 9% simple interest per annum. If he paid an amount of $8008 to clear the loan, then find the time period of the loan.

(2) What amount does Susan have to pay after 5 years if he takes a loan of $3650 at 3% simple interest?

(3) Calculate the amount due after 10 years if Linda borrowed a sum of $5350 at a rate of 4% simple interest.

(4) How much loan did James borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $6250 to clear it?

(5) Jennifer took a loan of $4500 at the rate of 8% simple interest per annum. If he paid an amount of $8100 to clear the loan, then find the time period of the loan.

(6) How much loan did Deborah borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $8195 to clear it?

(7) James had to pay $3180 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.

(8) Calculate the amount due if Patricia borrowed a sum of $3150 at 8% simple interest for 4 years.

(9) Karen took a loan of $5900 at the rate of 9% simple interest per annum. If he paid an amount of $9617 to clear the loan, then find the time period of the loan.

(10) What amount will be due after 2 years if Andrew borrowed a sum of $3900 at a 7% simple interest?