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) Robert took a loan of $4200 at the rate of 7% simple interest per annum. If he paid an amount of $7140 to clear the loan, then find the time period of the loan.

(2) Find the amount to be paid if Christopher borrowed a sum of $6000 at 10% simple interest for 8 years.

(3) How much loan did Mary borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $5807.5 to clear it?

(4) Margaret took a loan of $6700 at the rate of 8% simple interest per annum. If he paid an amount of $11524 to clear the loan, then find the time period of the loan.

(5) 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?

(6) What amount will be due after 2 years if Christopher borrowed a sum of $3500 at a 7% simple interest?

(7) How much loan did Sandra borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $7095 to clear it?

(8) Donald took a loan of $7000 at the rate of 6% simple interest per annum. If he paid an amount of $9940 to clear the loan, then find the time period of the loan.

(9) Find the amount to be paid if Jessica borrowed a sum of $5750 at 5% simple interest for 7 years.

(10) Calculate the amount due if Linda borrowed a sum of $3350 at 10% simple interest for 4 years.