Simple Interest
Math MCQs

Question :    Calculate the amount due if Elizabeth borrowed a sum of $3450 at 10% simple interest for 3 years.

Correct Answer  $4485

Solution & Explanation

Solution

Given,

Principal (P) = $3450

Rate of Simple Interest (SI) = 10%

Time (t) = 3 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) = $3450 × 10% × 3

= $3450 ×¹⁰/₁₀₀ × 3

= ^{3450 × 10 × 3}/₁₀₀

= ^{34500 × 3}/₁₀₀

= ¹⁰³⁵⁰⁰/₁₀₀

= $1035

Thus, Simple Interest = $1035

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 = $3450 + $1035

= $4485

Thus, Amount to be paid = $4485 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 = $3450

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

And, Time (t) = 3 years

Thus, Amount (A)

= $3450 + ($3450 × 10% × 3)

= $3450 + ($3450 ×¹⁰/₁₀₀ × 3)

= $3450 + (^{3450 × 10 × 3}/₁₀₀)

= $3450 + (^{34500 × 3}/₁₀₀)

= $3450 + (¹⁰³⁵⁰⁰/₁₀₀)

= $3450 + $1035 = $4485

Thus, Amount (A) to be paid = $4485 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 $3450, the simple interest in 1 year

= ¹⁰/₁₀₀ × 3450

= ^{10 × 3450}/₁₀₀

= ³⁴⁵⁰⁰/₁₀₀ = $345

Thus, simple interest for 1 year = $345

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $345 × 3 = $1035

Thus, Simple Interest (SI) = $1035

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3450 + $1035

= $4485

Thus, Amount to be paid = $4485 Answer

Similar Questions

(1) What amount will be due after 2 years if Steven borrowed a sum of $3800 at a 8% simple interest?

(2) Betty took a loan of $6500 at the rate of 10% simple interest per annum. If he paid an amount of $11050 to clear the loan, then find the time period of the loan.

(3) If Kimberly paid $5208 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(4) How much loan did Joshua borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $7590 to clear it?

(5) Jessica took a loan of $5500 at the rate of 10% simple interest per annum. If he paid an amount of $8800 to clear the loan, then find the time period of the loan.

(6) Calculate the amount due if John borrowed a sum of $3200 at 9% simple interest for 3 years.

(7) In how much time a principal of $3050 will amount to $3660 at a simple interest of 5% per annum?

(8) Charles took a loan of $5800 at the rate of 9% simple interest per annum. If he paid an amount of $10498 to clear the loan, then find the time period of the loan.

(9) Christopher took a loan of $6000 at the rate of 9% simple interest per annum. If he paid an amount of $11400 to clear the loan, then find the time period of the loan.

(10) Calculate the amount due after 10 years if Elizabeth borrowed a sum of $5450 at a rate of 4% simple interest.