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Finding the Fourth Proportional to 391.90, 587.42 and 209.11

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Solution

The fourth proportional to 391.90, 587.42 and 209.11 is: 313.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.90 : 587.42 = 209.11 : x
  2. Step 2: Convert to fraction form
    391.90/587.42 = 209.11/x
  3. Step 3: Cross multiply
    391.90x = 587.42 × 209.11
  4. Step 4: Simplify right side
    391.90x = 122,835.40
  5. Step 5: Solve for x
    x = 122,835.40/391.90
  6. Step 6: Final answer
    x = 313.44

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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.