Compare Fractions: Finding the Missing Sign Between 3/7 and 1/8

Fraction Comparison with Different Denominators

Fill in the missing sign:

3718 \frac{3}{7}☐\frac{1}{8}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Choose the appropriate sign
00:03 We want to find a common denominator
00:06 So we'll multiply each fraction by the denominator of the second fraction
00:09 Remember to multiply both numerator and denominator
00:20 Now we'll use the same method for the second fraction
00:23 Remember to multiply by the denominator of the second fraction
00:27 Remember to multiply both numerator and denominator
00:32 Now we have a common denominator between the fractions
00:37 When denominators are equal, the larger the numerator, the larger the fraction
00:44 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Fill in the missing sign:

3718 \frac{3}{7}☐\frac{1}{8}

2

Step-by-step solution

To solve this problem, we will compare the fractions 37\frac{3}{7} and 18\frac{1}{8} by converting them to have a common denominator.

Step 1: Find the least common multiple (LCM) of the denominators 7 and 8. Since 7 and 8 are coprime (have no common factors other than 1), the LCM is simply the product of the two numbers:

LCM(7,8)=7×8=56 \text{LCM}(7, 8) = 7 \times 8 = 56

Step 2: Convert each fraction to an equivalent fraction with the common denominator of 56.

  • Convert 37\frac{3}{7}:

  • 37=3×87×8=2456 \frac{3}{7} = \frac{3 \times 8}{7 \times 8} = \frac{24}{56}

  • Convert 18\frac{1}{8}:

  • 18=1×78×7=756 \frac{1}{8} = \frac{1 \times 7}{8 \times 7} = \frac{7}{56}

Step 3: Compare the new numerators:

2456and756 \frac{24}{56} \quad \text{and} \quad \frac{7}{56}

Since 24>724 > 7, we conclude that 2456>756\frac{24}{56} > \frac{7}{56}.

Therefore, the original inequality we are solving is:

37>18 \frac{3}{7} > \frac{1}{8}

Thus, the correct sign to fill in the blank is >\bm{>}.

3

Final Answer

> >

Key Points to Remember

Essential concepts to master this topic
  • Rule: Convert fractions to common denominator before comparing values
  • Technique: Find LCM of 7 and 8: 7×8=56 7 \times 8 = 56
  • Check: Compare numerators: 24 > 7, so 37>18 \frac{3}{7} > \frac{1}{8}

Common Mistakes

Avoid these frequent errors
  • Comparing denominators instead of converting to common denominators
    Don't just compare 7 vs 8 and think the larger denominator makes a bigger fraction = wrong answer! Larger denominators actually make smaller pieces. Always convert both fractions to the same denominator first, then compare numerators.

Practice Quiz

Test your knowledge with interactive questions

Fill in the missing sign:

\( \frac{5}{9}☐\frac{3}{9} \)

FAQ

Everything you need to know about this question

Why can't I just compare 3 with 1 and 7 with 8 separately?

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Because fractions represent parts of different wholes! 37 \frac{3}{7} means 3 pieces out of 7, while 18 \frac{1}{8} means 1 piece out of 8. You need the same-sized pieces to compare fairly.

How do I find the LCM of the denominators?

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For coprime numbers (no common factors like 7 and 8), just multiply them: 7×8=56 7 \times 8 = 56 . For other numbers, find the smallest number both denominators divide into evenly.

Is there a faster way to compare fractions?

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Yes! You can cross-multiply: compare 3×8=24 3 \times 8 = 24 with 1×7=7 1 \times 7 = 7 . Since 24 > 7, we know 37>18 \frac{3}{7} > \frac{1}{8} .

What if the fractions were equal?

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If the numerators are equal after converting to a common denominator, then the fractions are equal! For example, 23=46 \frac{2}{3} = \frac{4}{6} because both equal 46 \frac{4}{6} .

Does the order matter when I convert fractions?

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No! You can convert either fraction first, or both at the same time. The important thing is that both fractions end up with the same denominator so you can compare them fairly.

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