Simple Interest
Math MCQs

Question :    Calculate the amount due if James borrowed a sum of $3000 at 7% simple interest for 3 years.

Correct Answer  $3630

Solution & Explanation

Solution

Given,

Principal (P) = $3000

Rate of Simple Interest (SI) = 7%

Time (t) = 3 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) = $3000 × 7% × 3

= $3000 ×⁷/₁₀₀ × 3

= ^{3000 × 7 × 3}/₁₀₀

= ^{21000 × 3}/₁₀₀

= ⁶³⁰⁰⁰/₁₀₀

= $630

Thus, Simple Interest = $630

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 = $3000 + $630

= $3630

Thus, Amount to be paid = $3630 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 = $3000

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

And, Time (t) = 3 years

Thus, Amount (A)

= $3000 + ($3000 × 7% × 3)

= $3000 + ($3000 ×⁷/₁₀₀ × 3)

= $3000 + (^{3000 × 7 × 3}/₁₀₀)

= $3000 + (^{21000 × 3}/₁₀₀)

= $3000 + (⁶³⁰⁰⁰/₁₀₀)

= $3000 + $630 = $3630

Thus, Amount (A) to be paid = $3630 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 $3000, the simple interest in 1 year

= ⁷/₁₀₀ × 3000

= ^{7 × 3000}/₁₀₀

= ²¹⁰⁰⁰/₁₀₀ = $210

Thus, simple interest for 1 year = $210

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $210 × 3 = $630

Thus, Simple Interest (SI) = $630

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3000 + $630

= $3630

Thus, Amount to be paid = $3630 Answer

Similar Questions

(1) How much loan did Daniel borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $7015 to clear it?

(2) Calculate the amount due if William borrowed a sum of $3500 at 4% simple interest for 3 years.

(3) If James paid $3240 to settle his loan which he had taken 4 years before at a simple interest of 2%, then find the loan taken.

(4) What amount does Charles have to pay after 5 years if he takes a loan of $3900 at 3% simple interest?

(5) Find the amount to be paid if William borrowed a sum of $5500 at 3% simple interest for 8 years.

(6) Calculate the amount due if Sarah borrowed a sum of $3850 at 6% simple interest for 3 years.

(7) How much loan did Carol borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $8812.5 to clear it?

(8) Find the amount to be paid if Charles borrowed a sum of $5900 at 3% simple interest for 8 years.

(9) What amount will be due after 2 years if Thomas borrowed a sum of $3400 at a 10% simple interest?

(10) How much loan did John borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $6500 to clear it?