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Finding the Fourth Proportional to 385.78, 578.70 and 139.04

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Solution

The fourth proportional to 385.78, 578.70 and 139.04 is: 208.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    385.78 : 578.70 = 139.04 : x
  2. Step 2: Convert to fraction form
    385.78/578.70 = 139.04/x
  3. Step 3: Cross multiply
    385.78x = 578.70 × 139.04
  4. Step 4: Simplify right side
    385.78x = 80,459.55
  5. Step 5: Solve for x
    x = 80,459.55/385.78
  6. Step 6: Final answer
    x = 208.56

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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.