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Finding the Fourth Proportional to 80.61, 111.15 and 71.91

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Solution

The fourth proportional to 80.61, 111.15 and 71.91 is: 99.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.61 : 111.15 = 71.91 : x
  2. Step 2: Convert to fraction form
    80.61/111.15 = 71.91/x
  3. Step 3: Cross multiply
    80.61x = 111.15 × 71.91
  4. Step 4: Simplify right side
    80.61x = 7,992.80
  5. Step 5: Solve for x
    x = 7,992.80/80.61
  6. Step 6: Final answer
    x = 99.15

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.