Simple Interest
Math MCQs

Question :    Find the amount to be paid if William borrowed a sum of $5500 at 6% simple interest for 7 years.

Correct Answer  $7810

Solution & Explanation

Solution

Given,

Principal (P) = $5500

Rate of Simple Interest (SI) = 6%

Time (t) = 7 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) = $5500 × 6% × 7

= $5500 ×⁶/₁₀₀ × 7

= ^{5500 × 6 × 7}/₁₀₀

= ^{33000 × 7}/₁₀₀

= ²³¹⁰⁰⁰/₁₀₀

= $2310

Thus, Simple Interest = $2310

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 + $2310

= $7810

Thus, Amount to be paid = $7810 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) = 6%

And, Time (t) = 7 years

Thus, Amount (A)

= $5500 + ($5500 × 6% × 7)

= $5500 + ($5500 ×⁶/₁₀₀ × 7)

= $5500 + (^{5500 × 6 × 7}/₁₀₀)

= $5500 + (^{33000 × 7}/₁₀₀)

= $5500 + (²³¹⁰⁰⁰/₁₀₀)

= $5500 + $2310 = $7810

Thus, Amount (A) to be paid = $7810 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 $5500, the simple interest in 1 year

= ⁶/₁₀₀ × 5500

= ^{6 × 5500}/₁₀₀

= ³³⁰⁰⁰/₁₀₀ = $330

Thus, simple interest for 1 year = $330

Therefore, simple interest for 7 years

= Simple interest for 1 year × 7

= $330 × 7 = $2310

Thus, Simple Interest (SI) = $2310

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5500 + $2310

= $7810

Thus, Amount to be paid = $7810 Answer

Similar Questions

(1) If John borrowed $3200 from a bank at a rate of 2% simple interest per annum then find the amount to be paid after 2 years.

(2) What amount does Mary have to pay after 5 years if he takes a loan of $3050 at 3% simple interest?

(3) Calculate the amount due if Christopher borrowed a sum of $4000 at 3% simple interest for 4 years.

(4) What amount does William have to pay after 6 years if he takes a loan of $3500 at 9% simple interest?

(5) Calculate the amount due after 9 years if Susan borrowed a sum of $5650 at a rate of 4% simple interest.

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

(7) Joseph had to pay $4033 in order to furnish the loan taken 3 years before. If the rate of simple interest was 3% then find the sum borrowed.

(8) Calculate the amount due after 10 years if David borrowed a sum of $5400 at a rate of 9% simple interest.

(9) How much loan did Kenneth borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $7700 to clear it?

(10) Richard took a loan of $5200 at the rate of 8% simple interest per annum. If he paid an amount of $8944 to clear the loan, then find the time period of the loan.