Simple Interest
Math MCQs

Question :    Paul had to pay $5264 in order to furnish the loan taken 3 years before. If the rate of simple interest was 4% then find the sum borrowed.

Correct Answer  $4700

Solution & Explanation

Solution

Given,

Amount (A) = $5264

Rate of Simple Interest (R) = 4%

Time (T) = 3 years

Thus, Principal (P) = ?

Method (1) Using Formula

Calculation of the Principal using forumula when Amount, Time and Rate of Simple Interest are given

Formula to find the Principal (P)

Amount (A) = Principal (P) + Principal (P) × Rate (R) × Time (T)

⇒ Amount (A) = Principal (P) [1 + Rate (R) × Time (T)]

⇒ A = P (1 + RT)

Using the formula to find the Amount (A), the fourth can be calculated if any three of A, P, R, and T are given

In the given question, we need to find the Principal (P)

Therefore, by substituting, Amount, Rate, and Time, in the formula A = P (1 + RT) we get

$5264 = P (1 + 4% × 3)

⇒ $5264 = P (1 + ⁴/₁₀₀ × 3)

⇒ $5264 = P (1 + ^{4 × 3}/₁₀₀)

⇒ $5264 = P (1 + ¹²/₁₀₀)

⇒ $5264 = P (^{100 + 12}/₁₀₀)

⇒ $5264 = P × ¹¹²/₁₀₀

⇒ P × ¹¹²/₁₀₀ = $5264

⇒ P = ⁵²⁶⁴/_¹¹²/100

⇒ P = 5264 × ¹⁰⁰/₁₁₂

⇒ P = ^{5264 × 100}/₁₁₂

⇒ P = ⁵²⁶⁴⁰⁰/₁₁₂

⇒ P = $4700

Thus, the sum borrowed (P) = $4700 Answer

Method (1) Using Unitary Method

Calculation of the Principal using unitary method when Amount, Time and Rate of Simple Interest are given

Calculation of the Simple Interest

Let, the principal = 100

Here, since rate of simple interest = 4% per annum

Thus, Interest = 4% of principal

⇒ Interest = 4% of 100 = 4

Thus, Simple Interest for 1 year = 4

Calculation of the Amount

Since, in the question, time = 3 years

So, we need to calculate the simple interest for the given time period, which is 3 years

Thus, Simple Interest for 3 years = 3 × Simple Interest for 1 year

= 3 × 4 = 12

Thus, simple interest for 3 years = 12

Thus, Amount (A) = Principal + Interest

⇒ Amount = 100 + 12 = 112

Calculation of the Principal

Now,

∵ If the Amount is 112, then the Principal = 100

∴ If the Amount is 1, then the Principal = ¹⁰⁰/₁₁₂

∴ If the Amount is 5264, then the Principal = ¹⁰⁰/₁₁₂ × 5264

= ^{100 × 5264}/₁₁₂

= ⁵²⁶⁴⁰⁰/₁₁₂

= 4700

Thus, Principal = $4700

Thus, the sum borrowed = $4700 Answer

Similar Questions

(1) What amount does Charles have to pay after 6 years if he takes a loan of $3900 at 9% simple interest?

(2) Calculate the amount due if Jessica borrowed a sum of $3750 at 5% simple interest for 3 years.

(3) If Ashley paid $5460 to settle his loan which he had taken 4 years before at a simple interest of 5%, then find the loan taken.

(4) Calculate the amount due after 10 years if Mary borrowed a sum of $5050 at a rate of 6% simple interest.

(5) What amount does Christopher have to pay after 6 years if he takes a loan of $4000 at 10% simple interest?

(6) What amount does Charles have to pay after 5 years if he takes a loan of $3900 at 2% simple interest?

(7) How much loan did John borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $5980 to clear it?

(8) James took a loan of $4000 at the rate of 9% simple interest per annum. If he paid an amount of $6520 to clear the loan, then find the time period of the loan.

(9) Thomas took a loan of $5600 at the rate of 7% simple interest per annum. If he paid an amount of $9128 to clear the loan, then find the time period of the loan.

(10) What amount does Thomas have to pay after 6 years if he takes a loan of $3800 at 5% simple interest?