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Finding the Fourth Proportional to 405.20, 555.86 and 399.74

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Solution

The fourth proportional to 405.20, 555.86 and 399.74 is: 548.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    405.20 : 555.86 = 399.74 : x
  2. Step 2: Convert to fraction form
    405.20/555.86 = 399.74/x
  3. Step 3: Cross multiply
    405.20x = 555.86 × 399.74
  4. Step 4: Simplify right side
    405.20x = 222,197.70
  5. Step 5: Solve for x
    x = 222,197.70/405.20
  6. Step 6: Final answer
    x = 548.36

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.