Question:
Charles had to pay $4134 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.
Correct Answer
$3900
Solution And Explanation
Solution
Given,
Amount (A) = $4134
Rate of Simple Interest (R) = 2%
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
$4134 = P (1 + 2% × 3)
⇒ $4134 = P (1 + 2/100 × 3)
⇒ $4134 = P (1 + 2 × 3/100)
⇒ $4134 = P (1 + 6/100)
⇒ $4134 = P (100 + 6/100)
⇒ $4134 = P × 106/100
⇒ P × 106/100 = $4134
⇒ P = 4134/106/100
⇒ P = 4134 × 100/106
⇒ P = 4134 × 100/106
⇒ P = 413400/106
⇒ P = $3900
Thus, the sum borrowed (P) = $3900 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 = 2% per annum
Thus, Interest = 2% of principal
⇒ Interest = 2% of 100 = 2
Thus, Simple Interest for 1 year = 2
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 × 2 = 6
Thus, simple interest for 3 years = 6
Thus, Amount (A) = Principal + Interest
⇒ Amount = 100 + 6 = 106
Calculation of the Principal
Now,
∵ If the Amount is 106, then the Principal = 100
∴ If the Amount is 1, then the Principal = 100/106
∴ If the Amount is 4134, then the Principal = 100/106 × 4134
= 100 × 4134/106
= 413400/106
= 3900
Thus, Principal = $3900
Thus, the sum borrowed = $3900 Answer
Similar Questions
(1) Calculate the amount due if Patricia borrowed a sum of $3150 at 3% simple interest for 3 years.
(2) Find the amount to be paid if Karen borrowed a sum of $5950 at 10% simple interest for 7 years.
(3) Find the amount to be paid if Michael borrowed a sum of $5300 at 7% simple interest for 8 years.
(4) Sarah took a loan of $5700 at the rate of 9% simple interest per annum. If he paid an amount of $10317 to clear the loan, then find the time period of the loan.
(5) What amount will be due after 2 years if Christopher borrowed a sum of $3500 at a 9% simple interest?
(6) 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.
(7) What amount does Richard have to pay after 6 years if he takes a loan of $3600 at 7% simple interest?
(8) Calculate the amount due if Jessica borrowed a sum of $3750 at 7% simple interest for 3 years.
(9) Sandra took a loan of $6900 at the rate of 7% simple interest per annum. If he paid an amount of $9798 to clear the loan, then find the time period of the loan.
(10) Calculate the amount due after 10 years if Linda borrowed a sum of $5350 at a rate of 5% simple interest.