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Finding the Fourth Proportional to 392.91, 542.21 and 215.87

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Solution

The fourth proportional to 392.91, 542.21 and 215.87 is: 297.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    392.91 : 542.21 = 215.87 : x
  2. Step 2: Convert to fraction form
    392.91/542.21 = 215.87/x
  3. Step 3: Cross multiply
    392.91x = 542.21 × 215.87
  4. Step 4: Simplify right side
    392.91x = 117,046.87
  5. Step 5: Solve for x
    x = 117,046.87/392.91
  6. Step 6: Final answer
    x = 297.90

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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.