Simple Interest
Math MCQs

Question :    Calculate the amount due after 10 years if Robert borrowed a sum of $5100 at a rate of 4% simple interest.

Correct Answer  $7140

Solution & Explanation

Solution

Given,

Principal (P) = $5100

Rate of Simple Interest (SI) = 4%

Time (t) = 10 years

Thus, Amount (A) = ?

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

Thus, here 4% simple interest means, Rate of Simple Interest (SI) is 4% 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) = $5100 × 4% × 10

= $5100 ×⁴/₁₀₀ × 10

= ^{5100 × 4 × 10}/₁₀₀

= ^{20400 × 10}/₁₀₀

= ²⁰⁴⁰⁰⁰/₁₀₀

= $2040

Thus, Simple Interest = $2040

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 = $5100 + $2040

= $7140

Thus, Amount to be paid = $7140 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 = $5100

Rate of Simple Interest (SI) or (R) = 4%

And, Time (t) = 10 years

Thus, Amount (A)

= $5100 + ($5100 × 4% × 10)

= $5100 + ($5100 ×⁴/₁₀₀ × 10)

= $5100 + (^{5100 × 4 × 10}/₁₀₀)

= $5100 + (^{20400 × 10}/₁₀₀)

= $5100 + (²⁰⁴⁰⁰⁰/₁₀₀)

= $5100 + $2040 = $7140

Thus, Amount (A) to be paid = $7140 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 4%

This, means, $4 per $100 per year

∵ For $100, the simple interest for 1 year = $4

∴ For $1, the simple interest for 1 year = ⁴/₁₀₀

∴ For $5100, the simple interest in 1 year

= ⁴/₁₀₀ × 5100

= ^{4 × 5100}/₁₀₀

= ²⁰⁴⁰⁰/₁₀₀ = $204

Thus, simple interest for 1 year = $204

Therefore, simple interest for 10 years

= Simple interest for 1 year × 10

= $204 × 10 = $2040

Thus, Simple Interest (SI) = $2040

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5100 + $2040

= $7140

Thus, Amount to be paid = $7140 Answer

Similar Questions

(1) Find the amount to be paid if Jennifer borrowed a sum of $5250 at 9% simple interest for 7 years.

(2) How much loan did Joseph borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $6555 to clear it?

(3) Calculate the amount due if Susan borrowed a sum of $3650 at 3% simple interest for 4 years.

(4) Find the amount to be paid if Charles borrowed a sum of $5900 at 10% simple interest for 8 years.

(5) What amount will be due after 2 years if Steven borrowed a sum of $3800 at a 5% simple interest?

(6) What amount does Thomas have to pay after 5 years if he takes a loan of $3800 at 6% simple interest?

(7) If Kimberly paid $5022 to settle his loan which he had taken 4 years before at a simple interest of 2%, then find the loan taken.

(8) Find the amount to be paid if Charles borrowed a sum of $5900 at 8% simple interest for 8 years.

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

(10) Calculate the amount due if Joseph borrowed a sum of $3700 at 8% simple interest for 4 years.