Simple Interest
Math MCQs

Question :    Calculate the amount due after 10 years if Robert borrowed a sum of $5100 at a rate of 6% simple interest.

Correct Answer  $8160

Solution & Explanation

Solution

Given,

Principal (P) = $5100

Rate of Simple Interest (SI) = 6%

Time (t) = 10 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) = $5100 × 6% × 10

= $5100 ×⁶/₁₀₀ × 10

= ^{5100 × 6 × 10}/₁₀₀

= ^{30600 × 10}/₁₀₀

= ³⁰⁶⁰⁰⁰/₁₀₀

= $3060

Thus, Simple Interest = $3060

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 = $5100 + $3060

= $8160

Thus, Amount to be paid = $8160 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 = $5100

Rate of Simple Interest (SI) or (R) = 6%

And, Time (t) = 10 years

Thus, Amount (A)

= $5100 + ($5100 × 6% × 10)

= $5100 + ($5100 ×⁶/₁₀₀ × 10)

= $5100 + (^{5100 × 6 × 10}/₁₀₀)

= $5100 + (^{30600 × 10}/₁₀₀)

= $5100 + (³⁰⁶⁰⁰⁰/₁₀₀)

= $5100 + $3060 = $8160

Thus, Amount (A) to be paid = $8160 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 $5100, the simple interest in 1 year

= ⁶/₁₀₀ × 5100

= ^{6 × 5100}/₁₀₀

= ³⁰⁶⁰⁰/₁₀₀ = $306

Thus, simple interest for 1 year = $306

Therefore, simple interest for 10 years

= Simple interest for 1 year × 10

= $306 × 10 = $3060

Thus, Simple Interest (SI) = $3060

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5100 + $3060

= $8160

Thus, Amount to be paid = $8160 Answer

Similar Questions

(1) Calculate the amount due if Linda borrowed a sum of $3350 at 3% simple interest for 4 years.

(2) Margaret took a loan of $6700 at the rate of 9% simple interest per annum. If he paid an amount of $10921 to clear the loan, then find the time period of the loan.

(3) Margaret took a loan of $6700 at the rate of 6% simple interest per annum. If he paid an amount of $9514 to clear the loan, then find the time period of the loan.

(4) Calculate the amount due after 9 years if Robert borrowed a sum of $5100 at a rate of 3% simple interest.

(5) Matthew took a loan of $6400 at the rate of 6% simple interest per annum. If he paid an amount of $9856 to clear the loan, then find the time period of the loan.

(6) How much loan did Richard borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $6160 to clear it?

(7) Calculate the amount due if Patricia borrowed a sum of $3150 at 9% simple interest for 3 years.

(8) Anthony took a loan of $6600 at the rate of 10% simple interest per annum. If he paid an amount of $10560 to clear the loan, then find the time period of the loan.

(9) Calculate the amount due after 9 years if John borrowed a sum of $5200 at a rate of 7% simple interest.

(10) How much loan did Paul borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $8375 to clear it?