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Finding the Fourth Proportional to 80.69, 120.91 and 57.91

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Solution

The fourth proportional to 80.69, 120.91 and 57.91 is: 86.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.69 : 120.91 = 57.91 : x
  2. Step 2: Convert to fraction form
    80.69/120.91 = 57.91/x
  3. Step 3: Cross multiply
    80.69x = 120.91 × 57.91
  4. Step 4: Simplify right side
    80.69x = 7,001.45
  5. Step 5: Solve for x
    x = 7,001.45/80.69
  6. Step 6: Final answer
    x = 86.78

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.