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Finding the Fourth Proportional to 426.81, 639.21 and 280.47

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Solution

The fourth proportional to 426.81, 639.21 and 280.47 is: 420.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.81 : 639.21 = 280.47 : x
  2. Step 2: Convert to fraction form
    426.81/639.21 = 280.47/x
  3. Step 3: Cross multiply
    426.81x = 639.21 × 280.47
  4. Step 4: Simplify right side
    426.81x = 179,279.23
  5. Step 5: Solve for x
    x = 179,279.23/426.81
  6. Step 6: Final answer
    x = 420.04

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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.