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Question

Find the reciprocal of \(2\frac{3}{5}\).

The correct answer is \(\frac{5}{{13}}\)

Finding the Reciprocal of a Mixed Number

The question asks us to find the reciprocal of the mixed number \(2\frac{3}{5}\). Understanding how to work with reciprocals and mixed numbers is important for this problem.

What is a Reciprocal?

The reciprocal of a number is simply \(1\) divided by that number. Another way to think about it is finding a number that, when multiplied by the original number, gives a result of \(1\).

  • For a fraction \(\frac{a}{b}\), where \(a\) and \(b\) are non-zero, the reciprocal is \(\frac{b}{a}\). We just flip the numerator and the denominator.
  • For a whole number \(n\), we can think of it as the fraction \(\frac{n}{1}\). Its reciprocal is \(\frac{1}{n}\).

Converting the Mixed Number to an Improper Fraction

Before finding the reciprocal of a mixed number, it's easiest to convert it into an improper fraction. A mixed number like \(a\frac{b}{c}\) means \(a + \frac{b}{c}\). To convert it to an improper fraction, we use the formula \(\frac{(a \times c) + b}{c}\).

Let's convert \(2\frac{3}{5}\) to an improper fraction:

$$2\frac{3}{5} = \frac{(2 \times 5) + 3}{5} = \frac{10 + 3}{5} = \frac{13}{5}$$

So, the mixed number \(2\frac{3}{5}\) is equivalent to the improper fraction \(\frac{13}{5}\).

Calculating the Reciprocal

Now that we have the number as a fraction \(\frac{13}{5}\), we can easily find its reciprocal. The reciprocal of a fraction \(\frac{a}{b}\) is \(\frac{b}{a}\).

The reciprocal of \(\frac{13}{5}\) is found by flipping the numerator and the denominator:

$$\text{Reciprocal of } \frac{13}{5} = \frac{5}{13}$$

Verifying the Reciprocal

To verify that \(\frac{5}{13}\) is indeed the reciprocal of \(2\frac{3}{5}\) (or \(\frac{13}{5}\)), we can multiply the original number by its reciprocal. The result should be \(1\).

$$\frac{13}{5} \times \frac{5}{13} = \frac{13 \times 5}{5 \times 13} = \frac{65}{65} = 1$$

Since the product is \(1\), our calculation for the reciprocal is correct.

Final Answer for Reciprocal

The reciprocal of \(2\frac{3}{5}\) is \(\frac{5}{13}\).

Comparing this with the given options, we see that option 1 matches our result.

Revision Table: Understanding Reciprocals

Original Number Type How to Find Reciprocal Reciprocal
\(5\) Whole Number Think of it as \(\frac{5}{1}\), flip it. \(\frac{1}{5}\)
\(\frac{2}{3}\) Fraction Flip the numerator and denominator. \(\frac{3}{2}\)
\(1\frac{1}{2}\) Mixed Number Convert to improper fraction (\(1\frac{1}{2} = \frac{3}{2}\)), then flip. \(\frac{2}{3}\)
\(-4\) Negative Whole Number Think of it as \(\frac{-4}{1}\), flip it. \(\frac{1}{-4}\) or \(-\frac{1}{4}\)

Additional Information on Reciprocals and Fractions

  • The number \(0\) does not have a reciprocal, because division by zero is undefined.
  • The reciprocal of \(1\) is \(1\), and the reciprocal of \(-1\) is \(-1\).
  • Converting mixed numbers to improper fractions is a fundamental step in many fraction operations, including multiplication, division, and finding reciprocals.
  • Understanding reciprocals is essential for fraction division, as dividing by a fraction is the same as multiplying by its reciprocal. For example, \(\frac{a}{b} \div \frac{c}{d} = \frac{a}{b} \times \frac{d}{c}\).
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Important Questions from Integers

  1. The average of eleven consecutive positive integers is d. If the last two numbers are excluded, by how much will the average increase or decrease?
  2. The numerator of fraction is 3 more than the denominator. When 5 is added to the numerator and 2 is subtracted from the denominator, the fraction becomes 8/3, When the original fraction is divided by \(5 \frac{1}{2}\) , the fraction so obtained is:

  3. The sum of a non - zero number and twenty times its reciprocal is 9. What is the number?

  4. If \(\frac{{45}}{{53}} = \frac{1}{{a + \frac{1}{{b + \frac{1}{{c - \frac{2}{5}}}}}}},\)  where a, b and c are positive integers, then what is the value of (4a - b + 3c)

  5. The denominator of a fraction is 4 more than the double of its numerator. When 3 is added to the numerator and 3 is subtracted from denominator the fraction becomes 2/3. Then find the difference between denominator and numerator of the original fration. 

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