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Finding the Fourth Proportional to 398.78, 550.29 and 221.75

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Solution

The fourth proportional to 398.78, 550.29 and 221.75 is: 306.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    398.78 : 550.29 = 221.75 : x
  2. Step 2: Convert to fraction form
    398.78/550.29 = 221.75/x
  3. Step 3: Cross multiply
    398.78x = 550.29 × 221.75
  4. Step 4: Simplify right side
    398.78x = 122,026.95
  5. Step 5: Solve for x
    x = 122,026.95/398.78
  6. Step 6: Final answer
    x = 306.00

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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.