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Finding the Fourth Proportional to 86.61, 129.88 and 38.55

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Solution

The fourth proportional to 86.61, 129.88 and 38.55 is: 57.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.61 : 129.88 = 38.55 : x
  2. Step 2: Convert to fraction form
    86.61/129.88 = 38.55/x
  3. Step 3: Cross multiply
    86.61x = 129.88 × 38.55
  4. Step 4: Simplify right side
    86.61x = 5,006.87
  5. Step 5: Solve for x
    x = 5,006.87/86.61
  6. Step 6: Final answer
    x = 57.81

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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.