Simple Interest
MCQs Math


Question:     How much loan did Steven borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $8250 to clear it?


Correct Answer  $6600

Solution And Explanation

Solution

Given,

Amount (A) = $8250

Rate of Simple Interest (R) = 5%

Time (T) = 5 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

$8250 = P (1 + 5% × 5)

⇒ $8250 = P (1 + 5/100 × 5)

⇒ $8250 = P (1 + 5 × 5/100)

⇒ $8250 = P (1 + 25/100)

⇒ $8250 = P (100 + 25/100)

⇒ $8250 = P × 125/100

⇒ P × 125/100 = $8250

⇒ P = 8250/125/100

⇒ P = 8250 × 100/125

⇒ P = 8250 × 100/125

⇒ P = 825000/125

⇒ P = $6600

Thus, the sum borrowed (P) = $6600 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 = 5 years

So, we need to calculate the simple interest for the given time period, which is 5 years

Thus, Simple Interest for 5 years = 5 × Simple Interest for 1 year

= 5 × 5 = 25

Thus, simple interest for 5 years = 25

Thus, Amount (A) = Principal + Interest

⇒ Amount = 100 + 25 = 125

Calculation of the Principal

Now,

∵ If the Amount is 125, then the Principal = 100

∴ If the Amount is 1, then the Principal = 100/125

∴ If the Amount is 8250, then the Principal = 100/125 × 8250

= 100 × 8250/125

= 825000/125

= 6600

Thus, Principal = $6600

Thus, the sum borrowed = $6600 Answer


Similar Questions

(1) What amount does David have to pay after 5 years if he takes a loan of $3400 at 6% simple interest?

(2) Calculate the amount due after 10 years if Karen borrowed a sum of $5950 at a rate of 9% simple interest.

(3) What amount will be due after 2 years if Steven borrowed a sum of $3800 at a 5% simple interest?

(4) Charles took a loan of $5800 at the rate of 10% simple interest per annum. If he paid an amount of $10440 to clear the loan, then find the time period of the loan.

(5) Barbara took a loan of $5100 at the rate of 7% simple interest per annum. If he paid an amount of $8313 to clear the loan, then find the time period of the loan.

(6) Calculate the amount due if John borrowed a sum of $3200 at 3% simple interest for 4 years.

(7) If Ashley paid $5278 to settle his loan which he had taken 4 years before at a simple interest of 4%, then find the loan taken.

(8) Calculate the amount due after 10 years if Robert borrowed a sum of $5100 at a rate of 8% simple interest.

(9) Karen took a loan of $5900 at the rate of 8% simple interest per annum. If he paid an amount of $9676 to clear the loan, then find the time period of the loan.

(10) Calculate the amount due if Jessica borrowed a sum of $3750 at 3% simple interest for 4 years.


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