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Finding the Fourth Proportional to 81.86, 113.08 and 75.78

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Solution

The fourth proportional to 81.86, 113.08 and 75.78 is: 104.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.86 : 113.08 = 75.78 : x
  2. Step 2: Convert to fraction form
    81.86/113.08 = 75.78/x
  3. Step 3: Cross multiply
    81.86x = 113.08 × 75.78
  4. Step 4: Simplify right side
    81.86x = 8,569.20
  5. Step 5: Solve for x
    x = 8,569.20/81.86
  6. Step 6: Final answer
    x = 104.68

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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.