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Finding the Fourth Proportional to 391.78, 587.81 and 331.48

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Solution

The fourth proportional to 391.78, 587.81 and 331.48 is: 497.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.78 : 587.81 = 331.48 : x
  2. Step 2: Convert to fraction form
    391.78/587.81 = 331.48/x
  3. Step 3: Cross multiply
    391.78x = 587.81 × 331.48
  4. Step 4: Simplify right side
    391.78x = 194,847.26
  5. Step 5: Solve for x
    x = 194,847.26/391.78
  6. Step 6: Final answer
    x = 497.34

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.