Simple Interest
Math MCQs

Question :    What amount does Barbara have to pay after 6 years if he takes a loan of $3550 at 6% simple interest?

Correct Answer  $4828

Solution & Explanation

Solution

Given,

Principal (P) = $3550

Rate of Simple Interest (SI) = 6%

Time (t) = 6 years

Thus, Amount (A) = ?

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

Thus, here 6% simple interest means, Rate of Simple Interest (SI) is 6% 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 × 6% × 6

= $3550 ×⁶/₁₀₀ × 6

= ^{3550 × 6 × 6}/₁₀₀

= ^{21300 × 6}/₁₀₀

= ¹²⁷⁸⁰⁰/₁₀₀

= $1278

Thus, Simple Interest = $1278

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 + $1278

= $4828

Thus, Amount to be paid = $4828 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) = 6%

And, Time (t) = 6 years

Thus, Amount (A)

= $3550 + ($3550 × 6% × 6)

= $3550 + ($3550 ×⁶/₁₀₀ × 6)

= $3550 + (^{3550 × 6 × 6}/₁₀₀)

= $3550 + (^{21300 × 6}/₁₀₀)

= $3550 + (¹²⁷⁸⁰⁰/₁₀₀)

= $3550 + $1278 = $4828

Thus, Amount (A) to be paid = $4828 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 6%

This, means, $6 per $100 per year

∵ For $100, the simple interest for 1 year = $6

∴ For $1, the simple interest for 1 year = ⁶/₁₀₀

∴ For $3550, the simple interest in 1 year

= ⁶/₁₀₀ × 3550

= ^{6 × 3550}/₁₀₀

= ²¹³⁰⁰/₁₀₀ = $213

Thus, simple interest for 1 year = $213

Therefore, simple interest for 6 years

= Simple interest for 1 year × 6

= $213 × 6 = $1278

Thus, Simple Interest (SI) = $1278

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3550 + $1278

= $4828

Thus, Amount to be paid = $4828 Answer

Similar Questions

(1) What amount will be due after 2 years if Daniel borrowed a sum of $3550 at a 5% simple interest?

(2) Susan took a loan of $5300 at the rate of 7% simple interest per annum. If he paid an amount of $9010 to clear the loan, then find the time period of the loan.

(3) Calculate the amount due if Patricia borrowed a sum of $3150 at 6% simple interest for 3 years.

(4) Find the amount to be paid if Jessica borrowed a sum of $5750 at 2% simple interest for 7 years.

(5) Calculate the amount due if Robert borrowed a sum of $3100 at 8% simple interest for 3 years.

(6) Find the amount to be paid if Charles borrowed a sum of $5900 at 10% simple interest for 7 years.

(7) 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?

(8) How much loan did Daniel borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $6710 to clear it?

(9) Calculate the amount due if Richard borrowed a sum of $3600 at 7% simple interest for 4 years.

(10) In how much time a principal of $3050 will amount to $3507.5 at a simple interest of 3% per annum?