Simple Interest
Math MCQs

Question :    Calculate the amount due if Patricia borrowed a sum of $3150 at 5% simple interest for 4 years.

Correct Answer  $3780

Solution & Explanation

Solution

Given,

Principal (P) = $3150

Rate of Simple Interest (SI) = 5%

Time (t) = 4 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) = $3150 × 5% × 4

= $3150 ×⁵/₁₀₀ × 4

= ^{3150 × 5 × 4}/₁₀₀

= ^{15750 × 4}/₁₀₀

= ⁶³⁰⁰⁰/₁₀₀

= $630

Thus, Simple Interest = $630

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 + $630

= $3780

Thus, Amount to be paid = $3780 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) = 5%

And, Time (t) = 4 years

Thus, Amount (A)

= $3150 + ($3150 × 5% × 4)

= $3150 + ($3150 ×⁵/₁₀₀ × 4)

= $3150 + (^{3150 × 5 × 4}/₁₀₀)

= $3150 + (^{15750 × 4}/₁₀₀)

= $3150 + (⁶³⁰⁰⁰/₁₀₀)

= $3150 + $630 = $3780

Thus, Amount (A) to be paid = $3780 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 $3150, the simple interest in 1 year

= ⁵/₁₀₀ × 3150

= ^{5 × 3150}/₁₀₀

= ¹⁵⁷⁵⁰/₁₀₀ = $157.5

Thus, simple interest for 1 year = $157.5

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $157.5 × 4 = $630

Thus, Simple Interest (SI) = $630

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3150 + $630

= $3780

Thus, Amount to be paid = $3780 Answer

Similar Questions

(1) In how much time a principal of $3150 will amount to $3433.5 at a simple interest of 3% per annum?

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

(3) Calculate the amount due after 10 years if Richard borrowed a sum of $5600 at a rate of 10% simple interest.

(4) In how much time a principal of $3100 will amount to $3379 at a simple interest of 3% per annum?

(5) Calculate the amount due after 10 years if Charles borrowed a sum of $5900 at a rate of 7% simple interest.

(6) If Ashley paid $4914 to settle his loan which he had taken 4 years before at a simple interest of 2%, then find the loan taken.

(7) Calculate the amount due after 9 years if Charles borrowed a sum of $5900 at a rate of 9% simple interest.

(8) Calculate the amount due after 9 years if Sarah borrowed a sum of $5850 at a rate of 9% simple interest.

(9) If Kimberly paid $5208 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(10) What amount does Robert have to pay after 5 years if he takes a loan of $3100 at 3% simple interest?