Simple Interest
Math MCQs

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

Correct Answer  $4270

Solution & Explanation

Solution

Given,

Principal (P) = $3050

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) = $3050 × 10% × 4

= $3050 ×¹⁰/₁₀₀ × 4

= ^{3050 × 10 × 4}/₁₀₀

= ^{30500 × 4}/₁₀₀

= ¹²²⁰⁰⁰/₁₀₀

= $1220

Thus, Simple Interest = $1220

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 = $3050 + $1220

= $4270

Thus, Amount to be paid = $4270 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 = $3050

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

And, Time (t) = 4 years

Thus, Amount (A)

= $3050 + ($3050 × 10% × 4)

= $3050 + ($3050 ×¹⁰/₁₀₀ × 4)

= $3050 + (^{3050 × 10 × 4}/₁₀₀)

= $3050 + (^{30500 × 4}/₁₀₀)

= $3050 + (¹²²⁰⁰⁰/₁₀₀)

= $3050 + $1220 = $4270

Thus, Amount (A) to be paid = $4270 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 $3050, the simple interest in 1 year

= ¹⁰/₁₀₀ × 3050

= ^{10 × 3050}/₁₀₀

= ³⁰⁵⁰⁰/₁₀₀ = $305

Thus, simple interest for 1 year = $305

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $305 × 4 = $1220

Thus, Simple Interest (SI) = $1220

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3050 + $1220

= $4270

Thus, Amount to be paid = $4270 Answer

Similar Questions

(1) David took a loan of $4800 at the rate of 6% simple interest per annum. If he paid an amount of $7680 to clear the loan, then find the time period of the loan.

(2) What amount will be due after 2 years if Anthony borrowed a sum of $3650 at a 7% simple interest?

(3) 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.

(4) Steven had to pay $5152 in order to furnish the loan taken 3 years before. If the rate of simple interest was 4% then find the sum borrowed.

(5) Calculate the amount due if William borrowed a sum of $3500 at 4% simple interest for 4 years.

(6) Calculate the amount due if Elizabeth borrowed a sum of $3450 at 8% simple interest for 4 years.

(7) Lisa took a loan of $6100 at the rate of 7% simple interest per annum. If he paid an amount of $9516 to clear the loan, then find the time period of the loan.

(8) Calculate the amount due after 10 years if Mary borrowed a sum of $5050 at a rate of 3% simple interest.

(9) Calculate the amount due if Joseph borrowed a sum of $3700 at 7% simple interest for 4 years.

(10) What amount does Jessica have to pay after 5 years if he takes a loan of $3750 at 8% simple interest?