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Finding the Fourth Proportional to 386.78, 580.05 and 139.94

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Solution

The fourth proportional to 386.78, 580.05 and 139.94 is: 209.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    386.78 : 580.05 = 139.94 : x
  2. Step 2: Convert to fraction form
    386.78/580.05 = 139.94/x
  3. Step 3: Cross multiply
    386.78x = 580.05 × 139.94
  4. Step 4: Simplify right side
    386.78x = 81,172.20
  5. Step 5: Solve for x
    x = 81,172.20/386.78
  6. Step 6: Final answer
    x = 209.87

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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.