Simple Interest
Math MCQs

Question :  ( 1 of 10 )  Calculate the amount due after 9 years if Mary borrowed a sum of $5050 at a rate of 8% simple interest.

Correct Answer  $8686

Solution & Explanation

Solution

Given,

Principal (P) = $5050

Rate of Simple Interest (SI) = 8%

Time (t) = 9 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) = $5050 × 8% × 9

= $5050 ×⁸/₁₀₀ × 9

= ^{5050 × 8 × 9}/₁₀₀

= ^{40400 × 9}/₁₀₀

= ³⁶³⁶⁰⁰/₁₀₀

= $3636

Thus, Simple Interest = $3636

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 = $5050 + $3636

= $8686

Thus, Amount to be paid = $8686 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 = $5050

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

And, Time (t) = 9 years

Thus, Amount (A)

= $5050 + ($5050 × 8% × 9)

= $5050 + ($5050 ×⁸/₁₀₀ × 9)

= $5050 + (^{5050 × 8 × 9}/₁₀₀)

= $5050 + (^{40400 × 9}/₁₀₀)

= $5050 + (³⁶³⁶⁰⁰/₁₀₀)

= $5050 + $3636 = $8686

Thus, Amount (A) to be paid = $8686 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 $5050, the simple interest in 1 year

= ⁸/₁₀₀ × 5050

= ^{8 × 5050}/₁₀₀

= ⁴⁰⁴⁰⁰/₁₀₀ = $404

Thus, simple interest for 1 year = $404

Therefore, simple interest for 9 years

= Simple interest for 1 year × 9

= $404 × 9 = $3636

Thus, Simple Interest (SI) = $3636

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5050 + $3636

= $8686

Thus, Amount to be paid = $8686 Answer

Similar Questions

(1) What amount does Robert have to pay after 6 years if he takes a loan of $3100 at 9% simple interest?

(2) Richard took a loan of $5200 at the rate of 7% simple interest per annum. If he paid an amount of $8476 to clear the loan, then find the time period of the loan.

(3) How much loan did Joshua borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $8280 to clear it?

(4) Calculate the amount due after 9 years if David borrowed a sum of $5400 at a rate of 8% simple interest.

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

(6) Calculate the amount due if Michael borrowed a sum of $3300 at 3% simple interest for 4 years.

(7) Christopher took a loan of $6000 at the rate of 8% simple interest per annum. If he paid an amount of $10320 to clear the loan, then find the time period of the loan.

(8) Calculate the amount due after 10 years if Joseph borrowed a sum of $5700 at a rate of 7% simple interest.

(9) Jennifer took a loan of $4500 at the rate of 9% simple interest per annum. If he paid an amount of $6930 to clear the loan, then find the time period of the loan.

(10) In how much time a principal of $3000 will amount to $3240 at a simple interest of 4% per annum?