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Finding the Fourth Proportional to 76.91, 115.28 and 42.61

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Solution

The fourth proportional to 76.91, 115.28 and 42.61 is: 63.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.91 : 115.28 = 42.61 : x
  2. Step 2: Convert to fraction form
    76.91/115.28 = 42.61/x
  3. Step 3: Cross multiply
    76.91x = 115.28 × 42.61
  4. Step 4: Simplify right side
    76.91x = 4,912.08
  5. Step 5: Solve for x
    x = 4,912.08/76.91
  6. Step 6: Final answer
    x = 63.87

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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.