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Finding the Fourth Proportional to 86.15, 129.11 and 51.92

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Solution

The fourth proportional to 86.15, 129.11 and 51.92 is: 77.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.15 : 129.11 = 51.92 : x
  2. Step 2: Convert to fraction form
    86.15/129.11 = 51.92/x
  3. Step 3: Cross multiply
    86.15x = 129.11 × 51.92
  4. Step 4: Simplify right side
    86.15x = 6,702.97
  5. Step 5: Solve for x
    x = 6,702.97/86.15
  6. Step 6: Final answer
    x = 77.81

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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.