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Question

Which of the fractions given below, when added to 5/8, give 1?

This question was previously asked in
RRB ALP 2018 CBT 2 Fitter Question Paper (21-Jan-2019) (Shift 3)
The correct answer is

6/16

Understanding Fractions and Completing the Whole

The question asks us to find a fraction which, when added to $\frac{5}{8}$, results in the sum being equal to 1. The number 1 represents a whole.

Let the unknown fraction be represented by $x$. We can write the problem as an equation:

$\frac{5}{8} + x = 1$

To find the value of $x$, we need to isolate it. We can do this by subtracting $\frac{5}{8}$ from both sides of the equation:

$x = 1 - \frac{5}{8}$

To subtract a fraction from a whole number (1), we need to express the whole number 1 as a fraction with the same denominator as the fraction being subtracted. In this case, the denominator is 8. So, 1 can be written as $\frac{8}{8}$.

Now, the equation becomes:

$x = \frac{8}{8} - \frac{5}{8}$

Subtracting fractions with the same denominator is straightforward. We subtract the numerators and keep the denominator the same:

$x = \frac{8 - 5}{8}$

$x = \frac{3}{8}$

So, the fraction that needs to be added to $\frac{5}{8}$ to get 1 is $\frac{3}{8}$.

Now, let's look at the given options and see which one is equivalent to $\frac{3}{8}$.

  • Option 1: $\frac{6}{24}$. We can simplify this fraction by dividing both the numerator and the denominator by their greatest common divisor, which is 6. $\frac{6 \div 6}{24 \div 6} = \frac{1}{4}$. Is $\frac{1}{4}$ equal to $\frac{3}{8}$? No, because $\frac{1}{4}$ is equivalent to $\frac{2}{8}$ (by multiplying numerator and denominator by 2).
  • Option 2: $\frac{5}{2}$. This is an improper fraction, meaning its value is greater than 1 ($5 \div 2 = 2.5$). Adding a fraction greater than 1 to $\frac{5}{8}$ will result in a number much greater than 1. So, this is not the correct fraction.
  • Option 3: $\frac{6}{16}$. We can simplify this fraction by dividing both the numerator and the denominator by their greatest common divisor, which is 2. $\frac{6 \div 2}{16 \div 2} = \frac{3}{8}$. This fraction is exactly equal to the fraction we calculated ($\frac{3}{8}$).
  • Option 4: $\frac{6}{3}$. This fraction simplifies to a whole number. $\frac{6}{3} = 2$. Adding 2 to $\frac{5}{8}$ will result in a number much greater than 1. So, this is not the correct fraction.

Comparing the options to our calculated fraction $\frac{3}{8}$, we see that Option 3, $\frac{6}{16}$, is equivalent to $\frac{3}{8}$.

Let's check our answer:

$\frac{5}{8} + \frac{6}{16} = \frac{5}{8} + \frac{3}{8} = \frac{5+3}{8} = \frac{8}{8} = 1$

The sum is indeed 1, confirming that $\frac{6}{16}$ is the correct fraction.

The final answer is $\frac{6}{16}$.


Revision Table: Key Concepts for Fraction Addition

Understanding how to add and subtract fractions is crucial. Here’s a quick review:

Concept Explanation Example
Adding/Subtracting Fractions with Same Denominator Add or subtract the numerators and keep the denominator the same. $\frac{2}{7} + \frac{3}{7} = \frac{2+3}{7} = \frac{5}{7}$
Adding/Subtracting Fractions with Different Denominators Find a common denominator (often the least common multiple). Convert fractions to equivalent fractions with the common denominator. Then add or subtract. $\frac{1}{3} + \frac{1}{4}$. Common denominator is 12. $\frac{1}{3} = \frac{4}{12}$, $\frac{1}{4} = \frac{3}{12}$. Sum = $\frac{4}{12} + \frac{3}{12} = \frac{7}{12}$.
Simplifying Fractions Divide the numerator and the denominator by their greatest common divisor (GCD). $\frac{4}{8}$. GCD of 4 and 8 is 4. $\frac{4 \div 4}{8 \div 4} = \frac{1}{2}$.

Additional Information: Fractions and the Number 1

The number 1 plays a special role in fractions. Any fraction where the numerator is equal to the denominator (and the denominator is not zero) is equivalent to 1. Examples include $\frac{2}{2}$, $\frac{5}{5}$, $\frac{8}{8}$, $\frac{100}{100}$, etc.

When we talk about "completing" a fraction to make 1, we are essentially finding the difference between 1 and the given fraction. This is like finding the missing piece of a pie to make a whole pie.

For example, if you have $\frac{5}{8}$ of a pie, you need $1 - \frac{5}{8} = \frac{8}{8} - \frac{5}{8} = \frac{3}{8}$ more pie to have a whole pie. This illustrates the concept used in solving the problem.

Understanding equivalent fractions is also vital. Fractions like $\frac{3}{8}$, $\frac{6}{16}$, $\frac{9}{24}$, etc., all represent the same value, even though they have different numerators and denominators. This is because the ratio between the numerator and denominator is the same.

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Similar Questions

  1. A television show lasted for \(4\frac{2}{3}\) hours. If 1/5th of the total time was spent on advertisements, what was the actual duration of the television show?

  2. By what number should \(10\frac{2}{3}\) be divided to obtain 20?

  3. 23 × 31 = 713. How much is 0.0713 ÷ 3.1?

  4. A fraction, when taken away from \(\frac{1}{3}\)  gives  \(\frac{1}{12}\)  The fraction is:

  5. Tapan, Ravi and Trisha shared a cake. Tapan had 1/3 of it, Trisha had 1/2 of it and Ravi had the rest. What was Ravi’s share of the cake?

  6. Tapan, Ravi, and Trisha shared a cake. Tapan had 1/4 of it, Trisha had 2/3 of it and Ravi had the rest. What was Ravi’s share of the cake?

  7. The sum of two fraction is 19/20, one of them is 3/4. What is the other fraction?

  8. The sum of 4/7 and 7/4 is:

  9. 182/130 when written in the simplest form is:

  10. How much does one need to add to 4/5 to obtain 5/4?


Important Questions from Fractions

  1. 5 \(\frac{3}{4}\) + x + 2  \(\frac{1}{2}\) = 10  \(\frac{1}{8}\) Find the value of x.

  2. Simplify the expression 441 ÷  \(\left[270 \div \frac{3}{7}+\left(17\div \frac{1}{3}\right)-\left(8\frac{1}{2}-\frac{5}{2}\right)\right]\)

  3. Number 0.232323 can be written in rational form as:

  4. Solve: \(\frac{1}{2}\)  [{-2(2 + 3)*20}/2]

  5. Match the following.

    Column I

    Column II

    a.

    Equivalent fraction of \(\frac{7}{12}\)  is  

    i.

    Proper fraction

    b.

    Equivalent fraction of  \(\frac{9}{15}\)  is

    ii.

    Improper fraction

    c.

    \(\frac{7}{11}\)  is

    iii.

    \(\frac{21}{36}\)

    d.

    \(\frac{19}{5}\)  is

    iv.

    \(\frac{3}{5}\)

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