Simple Interest
Math MCQs

Question :    Calculate the amount due if Robert borrowed a sum of $3100 at 2% simple interest for 3 years.

Correct Answer  $3286

Solution & Explanation

Solution

Given,

Principal (P) = $3100

Rate of Simple Interest (SI) = 2%

Time (t) = 3 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) = $3100 × 2% × 3

= $3100 ײ/₁₀₀ × 3

= ^{3100 × 2 × 3}/₁₀₀

= ^{6200 × 3}/₁₀₀

= ¹⁸⁶⁰⁰/₁₀₀

= $186

Thus, Simple Interest = $186

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 = $3100 + $186

= $3286

Thus, Amount to be paid = $3286 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 = $3100

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

And, Time (t) = 3 years

Thus, Amount (A)

= $3100 + ($3100 × 2% × 3)

= $3100 + ($3100 ײ/₁₀₀ × 3)

= $3100 + (^{3100 × 2 × 3}/₁₀₀)

= $3100 + (^{6200 × 3}/₁₀₀)

= $3100 + (¹⁸⁶⁰⁰/₁₀₀)

= $3100 + $186 = $3286

Thus, Amount (A) to be paid = $3286 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 $3100, the simple interest in 1 year

= ²/₁₀₀ × 3100

= ^{2 × 3100}/₁₀₀

= ⁶²⁰⁰/₁₀₀ = $62

Thus, simple interest for 1 year = $62

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $62 × 3 = $186

Thus, Simple Interest (SI) = $186

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3100 + $186

= $3286

Thus, Amount to be paid = $3286 Answer

Similar Questions

(1) What amount does Susan have to pay after 6 years if he takes a loan of $3650 at 7% simple interest?

(2) What amount does Sarah have to pay after 6 years if he takes a loan of $3850 at 2% simple interest?

(3) If Linda paid $3752 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(4) What amount does Patricia have to pay after 6 years if he takes a loan of $3150 at 7% simple interest?

(5) What amount will be due after 2 years if Donald borrowed a sum of $3750 at a 8% simple interest?

(6) Jessica took a loan of $5500 at the rate of 8% simple interest per annum. If he paid an amount of $9900 to clear the loan, then find the time period of the loan.

(7) Find the amount to be paid if Susan borrowed a sum of $5650 at 8% simple interest for 7 years.

(8) What amount does Joseph have to pay after 5 years if he takes a loan of $3700 at 9% simple interest?

(9) If Joseph borrowed $3700 from a bank at a rate of 3% simple interest per annum then find the amount to be paid after 2 years.

(10) What amount will be due after 2 years if Donald borrowed a sum of $3750 at a 4% simple interest?