Simple Interest
Math MCQs

Question :    Calculate the amount due if Michael borrowed a sum of $3300 at 6% simple interest for 4 years.

Correct Answer  $4092

Solution & Explanation

Solution

Given,

Principal (P) = $3300

Rate of Simple Interest (SI) = 6%

Time (t) = 4 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) = $3300 × 6% × 4

= $3300 ×⁶/₁₀₀ × 4

= ^{3300 × 6 × 4}/₁₀₀

= ^{19800 × 4}/₁₀₀

= ⁷⁹²⁰⁰/₁₀₀

= $792

Thus, Simple Interest = $792

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 = $3300 + $792

= $4092

Thus, Amount to be paid = $4092 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 = $3300

Rate of Simple Interest (SI) or (R) = 6%

And, Time (t) = 4 years

Thus, Amount (A)

= $3300 + ($3300 × 6% × 4)

= $3300 + ($3300 ×⁶/₁₀₀ × 4)

= $3300 + (^{3300 × 6 × 4}/₁₀₀)

= $3300 + (^{19800 × 4}/₁₀₀)

= $3300 + (⁷⁹²⁰⁰/₁₀₀)

= $3300 + $792 = $4092

Thus, Amount (A) to be paid = $4092 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 $3300, the simple interest in 1 year

= ⁶/₁₀₀ × 3300

= ^{6 × 3300}/₁₀₀

= ¹⁹⁸⁰⁰/₁₀₀ = $198

Thus, simple interest for 1 year = $198

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $198 × 4 = $792

Thus, Simple Interest (SI) = $792

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3300 + $792

= $4092

Thus, Amount to be paid = $4092 Answer

Similar Questions

(1) Calculate the amount due if Robert borrowed a sum of $3100 at 6% simple interest for 3 years.

(2) Calculate the amount due if Richard borrowed a sum of $3600 at 4% simple interest for 3 years.

(3) If William paid $4200 to settle his loan which he had taken 4 years before at a simple interest of 5%, then find the loan taken.

(4) Calculate the amount due if Karen borrowed a sum of $3950 at 9% simple interest for 3 years.

(5) What amount does Robert have to pay after 6 years if he takes a loan of $3100 at 3% simple interest?

(6) Paul had to pay $5264 in order to furnish the loan taken 3 years before. If the rate of simple interest was 4% then find the sum borrowed.

(7) Find the amount to be paid if John borrowed a sum of $5200 at 3% simple interest for 7 years.

(8) How much loan did Christopher borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $6900 to clear it?

(9) How much loan did Nancy borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $7380 to clear it?

(10) What amount does Barbara have to pay after 6 years if he takes a loan of $3550 at 9% simple interest?