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Finding the Fourth Proportional to 391.86, 587.04 and 209.20

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Solution

The fourth proportional to 391.86, 587.04 and 209.20 is: 313.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.86 : 587.04 = 209.20 : x
  2. Step 2: Convert to fraction form
    391.86/587.04 = 209.20/x
  3. Step 3: Cross multiply
    391.86x = 587.04 × 209.20
  4. Step 4: Simplify right side
    391.86x = 122,808.77
  5. Step 5: Solve for x
    x = 122,808.77/391.86
  6. Step 6: Final answer
    x = 313.40

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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.