Simple Interest
Math MCQs

Question :    Find the amount to be paid if Barbara borrowed a sum of $5550 at 10% simple interest for 7 years.

Correct Answer  $9435

Solution & Explanation

Solution

Given,

Principal (P) = $5550

Rate of Simple Interest (SI) = 10%

Time (t) = 7 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) = $5550 × 10% × 7

= $5550 ×¹⁰/₁₀₀ × 7

= ^{5550 × 10 × 7}/₁₀₀

= ^{55500 × 7}/₁₀₀

= ³⁸⁸⁵⁰⁰/₁₀₀

= $3885

Thus, Simple Interest = $3885

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 = $5550 + $3885

= $9435

Thus, Amount to be paid = $9435 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 = $5550

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

And, Time (t) = 7 years

Thus, Amount (A)

= $5550 + ($5550 × 10% × 7)

= $5550 + ($5550 ×¹⁰/₁₀₀ × 7)

= $5550 + (^{5550 × 10 × 7}/₁₀₀)

= $5550 + (^{55500 × 7}/₁₀₀)

= $5550 + (³⁸⁸⁵⁰⁰/₁₀₀)

= $5550 + $3885 = $9435

Thus, Amount (A) to be paid = $9435 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 $5550, the simple interest in 1 year

= ¹⁰/₁₀₀ × 5550

= ^{10 × 5550}/₁₀₀

= ⁵⁵⁵⁰⁰/₁₀₀ = $555

Thus, simple interest for 1 year = $555

Therefore, simple interest for 7 years

= Simple interest for 1 year × 7

= $555 × 7 = $3885

Thus, Simple Interest (SI) = $3885

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5550 + $3885

= $9435

Thus, Amount to be paid = $9435 Answer

Similar Questions

(1) Christopher took a loan of $6000 at the rate of 6% simple interest per annum. If he paid an amount of $8880 to clear the loan, then find the time period of the loan.

(2) Michael took a loan of $4600 at the rate of 10% simple interest per annum. If he paid an amount of $8280 to clear the loan, then find the time period of the loan.

(3) Mark took a loan of $6800 at the rate of 8% simple interest per annum. If he paid an amount of $12240 to clear the loan, then find the time period of the loan.

(4) What amount does Christopher have to pay after 6 years if he takes a loan of $4000 at 8% simple interest?

(5) If John paid $3584 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(6) James took a loan of $4000 at the rate of 8% simple interest per annum. If he paid an amount of $6240 to clear the loan, then find the time period of the loan.

(7) Elizabeth took a loan of $4900 at the rate of 10% simple interest per annum. If he paid an amount of $8820 to clear the loan, then find the time period of the loan.

(8) Find the amount to be paid if Karen borrowed a sum of $5950 at 8% simple interest for 7 years.

(9) Calculate the amount due if Linda borrowed a sum of $3350 at 9% simple interest for 4 years.

(10) Calculate the amount due if Sarah borrowed a sum of $3850 at 9% simple interest for 3 years.