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Finding the Fourth Proportional to 391.72, 587.80 and 145.09

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Solution

The fourth proportional to 391.72, 587.80 and 145.09 is: 217.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.72 : 587.80 = 145.09 : x
  2. Step 2: Convert to fraction form
    391.72/587.80 = 145.09/x
  3. Step 3: Cross multiply
    391.72x = 587.80 × 145.09
  4. Step 4: Simplify right side
    391.72x = 85,285.73
  5. Step 5: Solve for x
    x = 85,285.73/391.72
  6. Step 6: Final answer
    x = 217.72

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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.