Simple Interest
Math MCQs

Question :    Calculate the amount due if Susan borrowed a sum of $3650 at 5% simple interest for 3 years.

Correct Answer  $4197.5

Solution & Explanation

Solution

Given,

Principal (P) = $3650

Rate of Simple Interest (SI) = 5%

Time (t) = 3 years

Thus, Amount (A) = ?

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

Thus, here 5% simple interest means, Rate of Simple Interest (SI) is 5% 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) = $3650 × 5% × 3

= $3650 ×⁵/₁₀₀ × 3

= ^{3650 × 5 × 3}/₁₀₀

= ^{18250 × 3}/₁₀₀

= ⁵⁴⁷⁵⁰/₁₀₀

= $547.5

Thus, Simple Interest = $547.5

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 = $3650 + $547.5

= $4197.5

Thus, Amount to be paid = $4197.5 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 = $3650

Rate of Simple Interest (SI) or (R) = 5%

And, Time (t) = 3 years

Thus, Amount (A)

= $3650 + ($3650 × 5% × 3)

= $3650 + ($3650 ×⁵/₁₀₀ × 3)

= $3650 + (^{3650 × 5 × 3}/₁₀₀)

= $3650 + (^{18250 × 3}/₁₀₀)

= $3650 + (⁵⁴⁷⁵⁰/₁₀₀)

= $3650 + $547.5 = $4197.5

Thus, Amount (A) to be paid = $4197.5 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 5%

This, means, $5 per $100 per year

∵ For $100, the simple interest for 1 year = $5

∴ For $1, the simple interest for 1 year = ⁵/₁₀₀

∴ For $3650, the simple interest in 1 year

= ⁵/₁₀₀ × 3650

= ^{5 × 3650}/₁₀₀

= ¹⁸²⁵⁰/₁₀₀ = $182.5

Thus, simple interest for 1 year = $182.5

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $182.5 × 3 = $547.5

Thus, Simple Interest (SI) = $547.5

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3650 + $547.5

= $4197.5

Thus, Amount to be paid = $4197.5 Answer

Similar Questions

(1) What amount does Thomas have to pay after 6 years if he takes a loan of $3800 at 7% simple interest?

(2) Calculate the amount due after 10 years if Linda borrowed a sum of $5350 at a rate of 4% simple interest.

(3) Robert took a loan of $4200 at the rate of 7% simple interest per annum. If he paid an amount of $7140 to clear the loan, then find the time period of the loan.

(4) If Emily paid $5700 to settle his loan which he had taken 4 years before at a simple interest of 5%, then find the loan taken.

(5) If James paid $3480 to settle his loan which he had taken 4 years before at a simple interest of 4%, then find the loan taken.

(6) Calculate the amount due if Richard borrowed a sum of $3600 at 8% simple interest for 3 years.

(7) Find the amount to be paid if Sarah borrowed a sum of $5850 at 5% simple interest for 7 years.

(8) John took a loan of $4400 at the rate of 10% simple interest per annum. If he paid an amount of $7040 to clear the loan, then find the time period of the loan.

(9) Calculate the amount due after 9 years if Joseph borrowed a sum of $5700 at a rate of 9% simple interest.

(10) What amount does Elizabeth have to pay after 5 years if he takes a loan of $3450 at 3% simple interest?