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Finding the Fourth Proportional to 77.31, 115.85 and 72.86

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Solution

The fourth proportional to 77.31, 115.85 and 72.86 is: 109.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.31 : 115.85 = 72.86 : x
  2. Step 2: Convert to fraction form
    77.31/115.85 = 72.86/x
  3. Step 3: Cross multiply
    77.31x = 115.85 × 72.86
  4. Step 4: Simplify right side
    77.31x = 8,439.89
  5. Step 5: Solve for x
    x = 8,439.89/77.31
  6. Step 6: Final answer
    x = 109.17

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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.