Simple Interest
Math MCQs

Question :    Calculate the amount due if Barbara borrowed a sum of $3550 at 7% simple interest for 4 years.

Correct Answer  $4544

Solution & Explanation

Solution

Given,

Principal (P) = $3550

Rate of Simple Interest (SI) = 7%

Time (t) = 4 years

Thus, Amount (A) = ?

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

Thus, here 7% simple interest means, Rate of Simple Interest (SI) is 7% 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) = $3550 × 7% × 4

= $3550 ×⁷/₁₀₀ × 4

= ^{3550 × 7 × 4}/₁₀₀

= ^{24850 × 4}/₁₀₀

= ⁹⁹⁴⁰⁰/₁₀₀

= $994

Thus, Simple Interest = $994

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 = $3550 + $994

= $4544

Thus, Amount to be paid = $4544 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 = $3550

Rate of Simple Interest (SI) or (R) = 7%

And, Time (t) = 4 years

Thus, Amount (A)

= $3550 + ($3550 × 7% × 4)

= $3550 + ($3550 ×⁷/₁₀₀ × 4)

= $3550 + (^{3550 × 7 × 4}/₁₀₀)

= $3550 + (^{24850 × 4}/₁₀₀)

= $3550 + (⁹⁹⁴⁰⁰/₁₀₀)

= $3550 + $994 = $4544

Thus, Amount (A) to be paid = $4544 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 7%

This, means, $7 per $100 per year

∵ For $100, the simple interest for 1 year = $7

∴ For $1, the simple interest for 1 year = ⁷/₁₀₀

∴ For $3550, the simple interest in 1 year

= ⁷/₁₀₀ × 3550

= ^{7 × 3550}/₁₀₀

= ²⁴⁸⁵⁰/₁₀₀ = $248.5

Thus, simple interest for 1 year = $248.5

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $248.5 × 4 = $994

Thus, Simple Interest (SI) = $994

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3550 + $994

= $4544

Thus, Amount to be paid = $4544 Answer

Similar Questions

(1) Find the amount to be paid if Charles borrowed a sum of $5900 at 7% simple interest for 8 years.

(2) Jennifer took a loan of $4500 at the rate of 7% simple interest per annum. If he paid an amount of $7650 to clear the loan, then find the time period of the loan.

(3) Find the amount to be paid if Michael borrowed a sum of $5300 at 5% simple interest for 8 years.

(4) James took a loan of $4000 at the rate of 7% simple interest per annum. If he paid an amount of $6800 to clear the loan, then find the time period of the loan.

(5) Find the amount to be paid if Linda borrowed a sum of $5350 at 8% simple interest for 7 years.

(6) Donald took a loan of $7000 at the rate of 9% simple interest per annum. If he paid an amount of $12040 to clear the loan, then find the time period of the loan.

(7) How much loan did Edward borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $8740 to clear it?

(8) What amount does Richard have to pay after 5 years if he takes a loan of $3600 at 7% simple interest?

(9) Calculate the amount due after 9 years if Joseph borrowed a sum of $5700 at a rate of 5% simple interest.

(10) Calculate the amount due if John borrowed a sum of $3200 at 4% simple interest for 3 years.