Simple Interest
Math MCQs

Question :    What amount does Patricia have to pay after 6 years if he takes a loan of $3150 at 3% simple interest?

Correct Answer  $3717

Solution & Explanation

Solution

Given,

Principal (P) = $3150

Rate of Simple Interest (SI) = 3%

Time (t) = 6 years

Thus, Amount (A) = ?

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

Thus, here 3% simple interest means, Rate of Simple Interest (SI) is 3% 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) = $3150 × 3% × 6

= $3150 ׳/₁₀₀ × 6

= ^{3150 × 3 × 6}/₁₀₀

= ^{9450 × 6}/₁₀₀

= ⁵⁶⁷⁰⁰/₁₀₀

= $567

Thus, Simple Interest = $567

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 = $3150 + $567

= $3717

Thus, Amount to be paid = $3717 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 = $3150

Rate of Simple Interest (SI) or (R) = 3%

And, Time (t) = 6 years

Thus, Amount (A)

= $3150 + ($3150 × 3% × 6)

= $3150 + ($3150 ׳/₁₀₀ × 6)

= $3150 + (^{3150 × 3 × 6}/₁₀₀)

= $3150 + (^{9450 × 6}/₁₀₀)

= $3150 + (⁵⁶⁷⁰⁰/₁₀₀)

= $3150 + $567 = $3717

Thus, Amount (A) to be paid = $3717 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 3%

This, means, $3 per $100 per year

∵ For $100, the simple interest for 1 year = $3

∴ For $1, the simple interest for 1 year = ³/₁₀₀

∴ For $3150, the simple interest in 1 year

= ³/₁₀₀ × 3150

= ^{3 × 3150}/₁₀₀

= ⁹⁴⁵⁰/₁₀₀ = $94.5

Thus, simple interest for 1 year = $94.5

Therefore, simple interest for 6 years

= Simple interest for 1 year × 6

= $94.5 × 6 = $567

Thus, Simple Interest (SI) = $567

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3150 + $567

= $3717

Thus, Amount to be paid = $3717 Answer

Similar Questions

(1) Margaret had to pay $4611 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.

(2) If Margaret paid $5046 to settle his loan which he had taken 4 years before at a simple interest of 4%, then find the loan taken.

(3) In how much time a principal of $3100 will amount to $3472 at a simple interest of 4% per annum?

(4) Calculate the amount due if Thomas borrowed a sum of $3800 at 3% simple interest for 4 years.

(5) How much loan did George borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $8395 to clear it?

(6) What amount does Susan have to pay after 5 years if he takes a loan of $3650 at 4% simple interest?

(7) Find the amount to be paid if Jennifer borrowed a sum of $5250 at 3% simple interest for 7 years.

(8) Jennifer took a loan of $4500 at the rate of 9% simple interest per annum. If he paid an amount of $6930 to clear the loan, then find the time period of the loan.

(9) Calculate the amount due if Susan borrowed a sum of $3650 at 10% simple interest for 4 years.

(10) How much loan did James borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $5500 to clear it?