Simple Interest
Math MCQs

Question :    What amount does Barbara have to pay after 6 years if he takes a loan of $3550 at 9% simple interest?

Correct Answer  $5467

Solution & Explanation

Solution

Given,

Principal (P) = $3550

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) = $3550 × 9% × 6

= $3550 ×⁹/₁₀₀ × 6

= ^{3550 × 9 × 6}/₁₀₀

= ^{31950 × 6}/₁₀₀

= ¹⁹¹⁷⁰⁰/₁₀₀

= $1917

Thus, Simple Interest = $1917

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 = $3550 + $1917

= $5467

Thus, Amount to be paid = $5467 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 = $3550

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

And, Time (t) = 6 years

Thus, Amount (A)

= $3550 + ($3550 × 9% × 6)

= $3550 + ($3550 ×⁹/₁₀₀ × 6)

= $3550 + (^{3550 × 9 × 6}/₁₀₀)

= $3550 + (^{31950 × 6}/₁₀₀)

= $3550 + (¹⁹¹⁷⁰⁰/₁₀₀)

= $3550 + $1917 = $5467

Thus, Amount (A) to be paid = $5467 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 $3550, the simple interest in 1 year

= ⁹/₁₀₀ × 3550

= ^{9 × 3550}/₁₀₀

= ³¹⁹⁵⁰/₁₀₀ = $319.5

Thus, simple interest for 1 year = $319.5

Therefore, simple interest for 6 years

= Simple interest for 1 year × 6

= $319.5 × 6 = $1917

Thus, Simple Interest (SI) = $1917

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3550 + $1917

= $5467

Thus, Amount to be paid = $5467 Answer

Similar Questions

(1) How much loan did Stephanie borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $9437.5 to clear it?

(2) Matthew took a loan of $6400 at the rate of 7% simple interest per annum. If he paid an amount of $9088 to clear the loan, then find the time period of the loan.

(3) What amount does Susan have to pay after 5 years if he takes a loan of $3650 at 9% simple interest?

(4) Calculate the amount due if Robert borrowed a sum of $3100 at 5% simple interest for 4 years.

(5) Nancy took a loan of $6300 at the rate of 9% simple interest per annum. If he paid an amount of $10836 to clear the loan, then find the time period of the loan.

(6) Find the amount to be paid if Patricia borrowed a sum of $5150 at 5% simple interest for 8 years.

(7) In how much time a principal of $3200 will amount to $3680 at a simple interest of 3% per annum?

(8) How much loan did Daniel borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $6710 to clear it?

(9) Find the amount to be paid if Sarah borrowed a sum of $5850 at 5% simple interest for 7 years.

(10) Joseph took a loan of $5400 at the rate of 7% simple interest per annum. If he paid an amount of $8424 to clear the loan, then find the time period of the loan.