Simple Interest
Math MCQs

Question :    Calculate the amount due after 9 years if William borrowed a sum of $5500 at a rate of 4% simple interest.

Correct Answer  $7480

Solution & Explanation

Solution

Given,

Principal (P) = $5500

Rate of Simple Interest (SI) = 4%

Time (t) = 9 years

Thus, Amount (A) = ?

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

Thus, here 4% simple interest means, Rate of Simple Interest (SI) is 4% 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) = $5500 × 4% × 9

= $5500 ×⁴/₁₀₀ × 9

= ^{5500 × 4 × 9}/₁₀₀

= ^{22000 × 9}/₁₀₀

= ¹⁹⁸⁰⁰⁰/₁₀₀

= $1980

Thus, Simple Interest = $1980

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 = $5500 + $1980

= $7480

Thus, Amount to be paid = $7480 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 = $5500

Rate of Simple Interest (SI) or (R) = 4%

And, Time (t) = 9 years

Thus, Amount (A)

= $5500 + ($5500 × 4% × 9)

= $5500 + ($5500 ×⁴/₁₀₀ × 9)

= $5500 + (^{5500 × 4 × 9}/₁₀₀)

= $5500 + (^{22000 × 9}/₁₀₀)

= $5500 + (¹⁹⁸⁰⁰⁰/₁₀₀)

= $5500 + $1980 = $7480

Thus, Amount (A) to be paid = $7480 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 4%

This, means, $4 per $100 per year

∵ For $100, the simple interest for 1 year = $4

∴ For $1, the simple interest for 1 year = ⁴/₁₀₀

∴ For $5500, the simple interest in 1 year

= ⁴/₁₀₀ × 5500

= ^{4 × 5500}/₁₀₀

= ²²⁰⁰⁰/₁₀₀ = $220

Thus, simple interest for 1 year = $220

Therefore, simple interest for 9 years

= Simple interest for 1 year × 9

= $220 × 9 = $1980

Thus, Simple Interest (SI) = $1980

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5500 + $1980

= $7480

Thus, Amount to be paid = $7480 Answer

Similar Questions

(1) Calculate the amount due after 9 years if David borrowed a sum of $5400 at a rate of 6% simple interest.

(2) Betty took a loan of $6500 at the rate of 9% simple interest per annum. If he paid an amount of $10010 to clear the loan, then find the time period of the loan.

(3) How much loan did Dorothy borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $7975 to clear it?

(4) What amount does Elizabeth have to pay after 6 years if he takes a loan of $3450 at 3% simple interest?

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

(6) How much loan did Kimberly borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $7980 to clear it?

(7) Find the amount to be paid if Mary borrowed a sum of $5050 at 9% simple interest for 7 years.

(8) If Elizabeth paid $3864 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(9) What amount does Joseph have to pay after 6 years if he takes a loan of $3700 at 8% simple interest?

(10) How much loan did Kevin borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $7810 to clear it?