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Finding the Fourth Proportional to 499.20, 687.47 and 405.78

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Solution

The fourth proportional to 499.20, 687.47 and 405.78 is: 558.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    499.20 : 687.47 = 405.78 : x
  2. Step 2: Convert to fraction form
    499.20/687.47 = 405.78/x
  3. Step 3: Cross multiply
    499.20x = 687.47 × 405.78
  4. Step 4: Simplify right side
    499.20x = 278,959.55
  5. Step 5: Solve for x
    x = 278,959.55/499.20
  6. Step 6: Final answer
    x = 558.81

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.