Question:
Patricia had to pay $3339 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
$3150
Solution And Explanation
Solution
Given,
Amount (A) = $3339
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
$3339 = P (1 + 2% × 3)
⇒ $3339 = P (1 + 2/100 × 3)
⇒ $3339 = P (1 + 2 × 3/100)
⇒ $3339 = P (1 + 6/100)
⇒ $3339 = P (100 + 6/100)
⇒ $3339 = P × 106/100
⇒ P × 106/100 = $3339
⇒ P = 3339/106/100
⇒ P = 3339 × 100/106
⇒ P = 3339 × 100/106
⇒ P = 333900/106
⇒ P = $3150
Thus, the sum borrowed (P) = $3150 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 3339, then the Principal = 100/106 × 3339
= 100 × 3339/106
= 333900/106
= 3150
Thus, Principal = $3150
Thus, the sum borrowed = $3150 Answer
Similar Questions
(1) Calculate the amount due if David borrowed a sum of $3400 at 4% simple interest for 4 years.
(2) What amount does Mary have to pay after 5 years if he takes a loan of $3050 at 8% simple interest?
(3) What amount does William have to pay after 5 years if he takes a loan of $3500 at 8% simple interest?
(4) Calculate the amount due if Jessica borrowed a sum of $3750 at 3% simple interest for 4 years.
(5) Barbara took a loan of $5100 at the rate of 9% simple interest per annum. If he paid an amount of $9231 to clear the loan, then find the time period of the loan.
(6) Find the amount to be paid if Mary borrowed a sum of $5050 at 10% simple interest for 8 years.
(7) What amount does Robert have to pay after 5 years if he takes a loan of $3100 at 4% simple interest?
(8) Find the amount to be paid if Joseph borrowed a sum of $5700 at 10% simple interest for 7 years.
(9) How much loan did Charles borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $7080 to clear it?
(10) Find the amount to be paid if Karen borrowed a sum of $5950 at 6% simple interest for 8 years.