Simple Interest
Math MCQs

Question :    Calculate the amount due if Patricia borrowed a sum of $3150 at 2% simple interest for 3 years.

Correct Answer  $3339

Solution & Explanation

Solution

Given,

Principal (P) = $3150

Rate of Simple Interest (SI) = 2%

Time (t) = 3 years

Thus, Amount (A) = ?

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

Thus, here 2% simple interest means, Rate of Simple Interest (SI) is 2% 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) = $3150 × 2% × 3

= $3150 ײ/₁₀₀ × 3

= ^{3150 × 2 × 3}/₁₀₀

= ^{6300 × 3}/₁₀₀

= ¹⁸⁹⁰⁰/₁₀₀

= $189

Thus, Simple Interest = $189

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 = $3150 + $189

= $3339

Thus, Amount to be paid = $3339 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 = $3150

Rate of Simple Interest (SI) or (R) = 2%

And, Time (t) = 3 years

Thus, Amount (A)

= $3150 + ($3150 × 2% × 3)

= $3150 + ($3150 ײ/₁₀₀ × 3)

= $3150 + (^{3150 × 2 × 3}/₁₀₀)

= $3150 + (^{6300 × 3}/₁₀₀)

= $3150 + (¹⁸⁹⁰⁰/₁₀₀)

= $3150 + $189 = $3339

Thus, Amount (A) to be paid = $3339 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 2%

This, means, $2 per $100 per year

∵ For $100, the simple interest for 1 year = $2

∴ For $1, the simple interest for 1 year = ²/₁₀₀

∴ For $3150, the simple interest in 1 year

= ²/₁₀₀ × 3150

= ^{2 × 3150}/₁₀₀

= ⁶³⁰⁰/₁₀₀ = $63

Thus, simple interest for 1 year = $63

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $63 × 3 = $189

Thus, Simple Interest (SI) = $189

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3150 + $189

= $3339

Thus, Amount to be paid = $3339 Answer

Similar Questions

(1) How much loan did Susan borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $6497.5 to clear it?

(2) Mary took a loan of $4100 at the rate of 9% simple interest per annum. If he paid an amount of $7421 to clear the loan, then find the time period of the loan.

(3) If Kimberly paid $5580 to settle his loan which he had taken 4 years before at a simple interest of 5%, then find the loan taken.

(4) Calculate the amount due if Mary borrowed a sum of $3050 at 10% simple interest for 4 years.

(5) If James borrowed $3000 from a bank at a rate of 3% simple interest per annum then find the amount to be paid after 2 years.

(6) Jennifer took a loan of $4500 at the rate of 7% simple interest per annum. If he paid an amount of $6390 to clear the loan, then find the time period of the loan.

(7) How much loan did Linda borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $6687.5 to clear it?

(8) What amount does Charles have to pay after 6 years if he takes a loan of $3900 at 8% simple interest?

(9) Thomas took a loan of $5600 at the rate of 7% simple interest per annum. If he paid an amount of $9520 to clear the loan, then find the time period of the loan.

(10) Elizabeth took a loan of $4900 at the rate of 6% simple interest per annum. If he paid an amount of $7840 to clear the loan, then find the time period of the loan.