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Finding the Fourth Proportional to 399.13, 550.21 and 280.72

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Solution

The fourth proportional to 399.13, 550.21 and 280.72 is: 386.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    399.13 : 550.21 = 280.72 : x
  2. Step 2: Convert to fraction form
    399.13/550.21 = 280.72/x
  3. Step 3: Cross multiply
    399.13x = 550.21 × 280.72
  4. Step 4: Simplify right side
    399.13x = 154,455.46
  5. Step 5: Solve for x
    x = 154,455.46/399.13
  6. Step 6: Final answer
    x = 386.98

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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.