Simple Interest
Math MCQs

Question :    Calculate the amount due if Charles borrowed a sum of $3900 at 2% simple interest for 4 years.

Correct Answer  $4212

Solution & Explanation

Solution

Given,

Principal (P) = $3900

Rate of Simple Interest (SI) = 2%

Time (t) = 4 years

Thus, Amount (A) = ?

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

Thus, here 2% simple interest means, Rate of Simple Interest (SI) is 2% 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) = $3900 × 2% × 4

= $3900 ײ/₁₀₀ × 4

= ^{3900 × 2 × 4}/₁₀₀

= ^{7800 × 4}/₁₀₀

= ³¹²⁰⁰/₁₀₀

= $312

Thus, Simple Interest = $312

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 = $3900 + $312

= $4212

Thus, Amount to be paid = $4212 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 = $3900

Rate of Simple Interest (SI) or (R) = 2%

And, Time (t) = 4 years

Thus, Amount (A)

= $3900 + ($3900 × 2% × 4)

= $3900 + ($3900 ײ/₁₀₀ × 4)

= $3900 + (^{3900 × 2 × 4}/₁₀₀)

= $3900 + (^{7800 × 4}/₁₀₀)

= $3900 + (³¹²⁰⁰/₁₀₀)

= $3900 + $312 = $4212

Thus, Amount (A) to be paid = $4212 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 2%

This, means, $2 per $100 per year

∵ For $100, the simple interest for 1 year = $2

∴ For $1, the simple interest for 1 year = ²/₁₀₀

∴ For $3900, the simple interest in 1 year

= ²/₁₀₀ × 3900

= ^{2 × 3900}/₁₀₀

= ⁷⁸⁰⁰/₁₀₀ = $78

Thus, simple interest for 1 year = $78

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $78 × 4 = $312

Thus, Simple Interest (SI) = $312

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3900 + $312

= $4212

Thus, Amount to be paid = $4212 Answer

Similar Questions

(1) What amount does Linda have to pay after 5 years if he takes a loan of $3350 at 5% simple interest?

(2) Calculate the amount due after 9 years if John borrowed a sum of $5200 at a rate of 6% simple interest.

(3) What amount will be due after 2 years if James borrowed a sum of $3000 at a 8% simple interest?

(4) James took a loan of $4000 at the rate of 10% simple interest per annum. If he paid an amount of $7200 to clear the loan, then find the time period of the loan.

(5) Find the amount to be paid if Patricia borrowed a sum of $5150 at 7% simple interest for 7 years.

(6) If Daniel paid $4428 to settle his loan which he had taken 4 years before at a simple interest of 2%, then find the loan taken.

(7) Daniel took a loan of $6200 at the rate of 9% simple interest per annum. If he paid an amount of $9548 to clear the loan, then find the time period of the loan.

(8) William took a loan of $5000 at the rate of 7% simple interest per annum. If he paid an amount of $7100 to clear the loan, then find the time period of the loan.

(9) Find the amount to be paid if David borrowed a sum of $5400 at 4% simple interest for 8 years.

(10) In how much time a principal of $3050 will amount to $3812.5 at a simple interest of 5% per annum?