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Finding the Fourth Proportional to 386.20, 579.33 and 139.42

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Solution

The fourth proportional to 386.20, 579.33 and 139.42 is: 209.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    386.20 : 579.33 = 139.42 : x
  2. Step 2: Convert to fraction form
    386.20/579.33 = 139.42/x
  3. Step 3: Cross multiply
    386.20x = 579.33 × 139.42
  4. Step 4: Simplify right side
    386.20x = 80,770.52
  5. Step 5: Solve for x
    x = 80,770.52/386.20
  6. Step 6: Final answer
    x = 209.14

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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.