Simple Interest
Math MCQs

Question :    Calculate the amount due if Susan borrowed a sum of $3650 at 10% simple interest for 4 years.

Correct Answer  $5110

Solution & Explanation

Solution

Given,

Principal (P) = $3650

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) = $3650 × 10% × 4

= $3650 ×¹⁰/₁₀₀ × 4

= ^{3650 × 10 × 4}/₁₀₀

= ^{36500 × 4}/₁₀₀

= ¹⁴⁶⁰⁰⁰/₁₀₀

= $1460

Thus, Simple Interest = $1460

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 = $3650 + $1460

= $5110

Thus, Amount to be paid = $5110 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 = $3650

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

And, Time (t) = 4 years

Thus, Amount (A)

= $3650 + ($3650 × 10% × 4)

= $3650 + ($3650 ×¹⁰/₁₀₀ × 4)

= $3650 + (^{3650 × 10 × 4}/₁₀₀)

= $3650 + (^{36500 × 4}/₁₀₀)

= $3650 + (¹⁴⁶⁰⁰⁰/₁₀₀)

= $3650 + $1460 = $5110

Thus, Amount (A) to be paid = $5110 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 $3650, the simple interest in 1 year

= ¹⁰/₁₀₀ × 3650

= ^{10 × 3650}/₁₀₀

= ³⁶⁵⁰⁰/₁₀₀ = $365

Thus, simple interest for 1 year = $365

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $365 × 4 = $1460

Thus, Simple Interest (SI) = $1460

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3650 + $1460

= $5110

Thus, Amount to be paid = $5110 Answer

Similar Questions

(1) What amount will be due after 2 years if Joseph borrowed a sum of $3350 at a 6% simple interest?

(2) Betty took a loan of $6500 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.

(3) Calculate the amount due if Mary borrowed a sum of $3050 at 3% simple interest for 4 years.

(4) What amount does Susan have to pay after 6 years if he takes a loan of $3650 at 3% simple interest?

(5) Calculate the amount due after 10 years if Karen borrowed a sum of $5950 at a rate of 3% simple interest.

(6) Sandra took a loan of $6900 at the rate of 9% simple interest per annum. If he paid an amount of $12489 to clear the loan, then find the time period of the loan.

(7) Calculate the amount due if Michael borrowed a sum of $3300 at 10% simple interest for 3 years.

(8) Calculate the amount due if Jennifer borrowed a sum of $3250 at 10% simple interest for 4 years.

(9) How much loan did Richard borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $6720 to clear it?

(10) In how much time a principal of $3100 will amount to $3410 at a simple interest of 5% per annum?