Is 5/7 Bigger Than 9/11?

Method 1: Common Denominators

To compare these fractions, we need a common denominator. The denominators are 7 and 11, and the least common denominator (LCD) is 77.

• Step 1. Convert \(\frac{5}{7}\): multiply numerator and denominator by 11.
  \[\frac{5}{7} = \frac{5 \times 11}{7 \times 11} = \frac{55}{77}\]
• Step 2. Convert \(\frac{9}{11}\): multiply numerator and denominator by 7.
  \[\frac{9}{11} = \frac{9 \times 7}{11 \times 7} = \frac{63}{77}\]
• Step 3. Compare the numerators: 55 vs 63.
• Step 4. Since 55 is less than 63, we know that \(\frac{5}{7} < \frac{9}{11}\).

Method 2: Cross Multiplication

A quicker way to compare fractions is to cross-multiply. Multiply each numerator by the other fraction's denominator:

• Step 1. Multiply the numerator of the first fraction by the denominator of the second: \(5 \times 11 = 55\).
• Step 2. Multiply the numerator of the second fraction by the denominator of the first: \(9 \times 7 = 63\).
• Step 3. Compare the products: \(55 < 63\), so \(\frac{5}{7} < \frac{9}{11}\).

Method 3: Decimal Comparison

Convert each fraction to a decimal by dividing the numerator by the denominator:

Since 0.714286 is less than 0.818182, we confirm that \(\frac{5}{7} < \frac{9}{11}\). In percentage terms, \(\frac{5}{7}\) is 71.4286% and \(\frac{9}{11}\) is 81.8182%, a difference of 10.3896 percentage points.

Why Does This Work?

These fractions have different numerators and different denominators, so we can't compare them directly. By converting to a common denominator of 77, we're cutting both quantities into equal-sized pieces. Then 55 pieces vs 63 pieces is a straightforward comparison.