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Finding the Fourth Proportional to 399.20, 551.00 and 251.78

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Solution

The fourth proportional to 399.20, 551.00 and 251.78 is: 347.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    399.20 : 551.00 = 251.78 : x
  2. Step 2: Convert to fraction form
    399.20/551.00 = 251.78/x
  3. Step 3: Cross multiply
    399.20x = 551.00 × 251.78
  4. Step 4: Simplify right side
    399.20x = 138,728.65
  5. Step 5: Solve for x
    x = 138,728.65/399.20
  6. Step 6: Final answer
    x = 347.52

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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.