Simple Interest
Math MCQs

Question :    Calculate the amount due if Robert borrowed a sum of $3100 at 6% simple interest for 4 years.

Correct Answer  $3844

Solution & Explanation

Solution

Given,

Principal (P) = $3100

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) = $3100 × 6% × 4

= $3100 ×⁶/₁₀₀ × 4

= ^{3100 × 6 × 4}/₁₀₀

= ^{18600 × 4}/₁₀₀

= ⁷⁴⁴⁰⁰/₁₀₀

= $744

Thus, Simple Interest = $744

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 = $3100 + $744

= $3844

Thus, Amount to be paid = $3844 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 = $3100

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

And, Time (t) = 4 years

Thus, Amount (A)

= $3100 + ($3100 × 6% × 4)

= $3100 + ($3100 ×⁶/₁₀₀ × 4)

= $3100 + (^{3100 × 6 × 4}/₁₀₀)

= $3100 + (^{18600 × 4}/₁₀₀)

= $3100 + (⁷⁴⁴⁰⁰/₁₀₀)

= $3100 + $744 = $3844

Thus, Amount (A) to be paid = $3844 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 $3100, the simple interest in 1 year

= ⁶/₁₀₀ × 3100

= ^{6 × 3100}/₁₀₀

= ¹⁸⁶⁰⁰/₁₀₀ = $186

Thus, simple interest for 1 year = $186

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $186 × 4 = $744

Thus, Simple Interest (SI) = $744

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3100 + $744

= $3844

Thus, Amount to be paid = $3844 Answer

Similar Questions

(1) What amount will be due after 2 years if Andrew borrowed a sum of $3900 at a 5% simple interest?

(2) Calculate the amount due after 10 years if Joseph borrowed a sum of $5700 at a rate of 9% simple interest.

(3) Margaret took a loan of $6700 at the rate of 7% simple interest per annum. If he paid an amount of $9514 to clear the loan, then find the time period of the loan.

(4) Betty took a loan of $6500 at the rate of 7% simple interest per annum. If he paid an amount of $10595 to clear the loan, then find the time period of the loan.

(5) What amount does Patricia have to pay after 6 years if he takes a loan of $3150 at 6% simple interest?

(6) How much loan did Ashley borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $7205 to clear it?

(7) How much loan did Dorothy borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $8700 to clear it?

(8) What amount does James have to pay after 6 years if he takes a loan of $3000 at 10% simple interest?

(9) Sandra took a loan of $6900 at the rate of 6% simple interest per annum. If he paid an amount of $9798 to clear the loan, then find the time period of the loan.

(10) How much loan did Deborah borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $8940 to clear it?