Simple Interest
Math MCQs

Question :    What amount does James have to pay after 6 years if he takes a loan of $3000 at 9% simple interest?

Correct Answer  $4620

Solution & Explanation

Solution

Given,

Principal (P) = $3000

Rate of Simple Interest (SI) = 9%

Time (t) = 6 years

Thus, Amount (A) = ?

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

Thus, here 9% simple interest means, Rate of Simple Interest (SI) is 9% 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) = $3000 × 9% × 6

= $3000 ×⁹/₁₀₀ × 6

= ^{3000 × 9 × 6}/₁₀₀

= ^{27000 × 6}/₁₀₀

= ¹⁶²⁰⁰⁰/₁₀₀

= $1620

Thus, Simple Interest = $1620

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 = $3000 + $1620

= $4620

Thus, Amount to be paid = $4620 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 = $3000

Rate of Simple Interest (SI) or (R) = 9%

And, Time (t) = 6 years

Thus, Amount (A)

= $3000 + ($3000 × 9% × 6)

= $3000 + ($3000 ×⁹/₁₀₀ × 6)

= $3000 + (^{3000 × 9 × 6}/₁₀₀)

= $3000 + (^{27000 × 6}/₁₀₀)

= $3000 + (¹⁶²⁰⁰⁰/₁₀₀)

= $3000 + $1620 = $4620

Thus, Amount (A) to be paid = $4620 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 9%

This, means, $9 per $100 per year

∵ For $100, the simple interest for 1 year = $9

∴ For $1, the simple interest for 1 year = ⁹/₁₀₀

∴ For $3000, the simple interest in 1 year

= ⁹/₁₀₀ × 3000

= ^{9 × 3000}/₁₀₀

= ²⁷⁰⁰⁰/₁₀₀ = $270

Thus, simple interest for 1 year = $270

Therefore, simple interest for 6 years

= Simple interest for 1 year × 6

= $270 × 6 = $1620

Thus, Simple Interest (SI) = $1620

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3000 + $1620

= $4620

Thus, Amount to be paid = $4620 Answer

Similar Questions

(1) What amount will be due after 2 years if Mark borrowed a sum of $3700 at a 5% simple interest?

(2) Sandra took a loan of $6900 at the rate of 8% simple interest per annum. If he paid an amount of $10764 to clear the loan, then find the time period of the loan.

(3) Lisa took a loan of $6100 at the rate of 9% simple interest per annum. If he paid an amount of $9943 to clear the loan, then find the time period of the loan.

(4) Find the amount to be paid if Robert borrowed a sum of $5100 at 4% simple interest for 8 years.

(5) What amount does Jennifer have to pay after 5 years if he takes a loan of $3250 at 4% simple interest?

(6) What amount does Joseph have to pay after 5 years if he takes a loan of $3700 at 10% simple interest?

(7) What amount does Linda have to pay after 6 years if he takes a loan of $3350 at 8% simple interest?

(8) Calculate the amount due after 9 years if Michael borrowed a sum of $5300 at a rate of 10% simple interest.

(9) If Steven paid $5520 to settle his loan which he had taken 4 years before at a simple interest of 5%, then find the loan taken.

(10) Calculate the amount due if Mary borrowed a sum of $3050 at 9% simple interest for 3 years.