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Finding the Fourth Proportional to 76.87, 115.31 and 42.65

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Solution

The fourth proportional to 76.87, 115.31 and 42.65 is: 63.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.87 : 115.31 = 42.65 : x
  2. Step 2: Convert to fraction form
    76.87/115.31 = 42.65/x
  3. Step 3: Cross multiply
    76.87x = 115.31 × 42.65
  4. Step 4: Simplify right side
    76.87x = 4,917.97
  5. Step 5: Solve for x
    x = 4,917.97/76.87
  6. Step 6: Final answer
    x = 63.98

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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.