Question:
Steven had to pay $5290 in order to furnish the loan taken 3 years before. If the rate of simple interest was 5% then find the sum borrowed.
Correct Answer
$4600
Solution And Explanation
Solution
Given,
Amount (A) = $5290
Rate of Simple Interest (R) = 5%
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
$5290 = P (1 + 5% × 3)
⇒ $5290 = P (1 + 5/100 × 3)
⇒ $5290 = P (1 + 5 × 3/100)
⇒ $5290 = P (1 + 15/100)
⇒ $5290 = P (100 + 15/100)
⇒ $5290 = P × 115/100
⇒ P × 115/100 = $5290
⇒ P = 5290/115/100
⇒ P = 5290 × 100/115
⇒ P = 5290 × 100/115
⇒ P = 529000/115
⇒ P = $4600
Thus, the sum borrowed (P) = $4600 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 = 5% per annum
Thus, Interest = 5% of principal
⇒ Interest = 5% of 100 = 5
Thus, Simple Interest for 1 year = 5
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 × 5 = 15
Thus, simple interest for 3 years = 15
Thus, Amount (A) = Principal + Interest
⇒ Amount = 100 + 15 = 115
Calculation of the Principal
Now,
∵ If the Amount is 115, then the Principal = 100
∴ If the Amount is 1, then the Principal = 100/115
∴ If the Amount is 5290, then the Principal = 100/115 × 5290
= 100 × 5290/115
= 529000/115
= 4600
Thus, Principal = $4600
Thus, the sum borrowed = $4600 Answer
Similar Questions
(1) What amount will be due after 2 years if Charles borrowed a sum of $3450 at a 8% simple interest?
(2) What amount does Patricia have to pay after 6 years if he takes a loan of $3150 at 3% simple interest?
(3) Calculate the amount due after 9 years if Charles borrowed a sum of $5900 at a rate of 3% simple interest.
(4) What amount does Jennifer have to pay after 5 years if he takes a loan of $3250 at 9% simple interest?
(5) What amount does Mary have to pay after 6 years if he takes a loan of $3050 at 5% simple interest?
(6) Robert took a loan of $4200 at the rate of 8% simple interest per annum. If he paid an amount of $7560 to clear the loan, then find the time period of the loan.
(7) How much loan did Ronald borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $8625 to clear it?
(8) How much loan did Ryan borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $9480 to clear it?
(9) What amount does Thomas have to pay after 6 years if he takes a loan of $3800 at 7% simple interest?
(10) Calculate the amount due after 10 years if Jessica borrowed a sum of $5750 at a rate of 3% simple interest.