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Finding the Fourth Proportional to 427.78, 641.77 and 139.22

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Solution

The fourth proportional to 427.78, 641.77 and 139.22 is: 208.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.78 : 641.77 = 139.22 : x
  2. Step 2: Convert to fraction form
    427.78/641.77 = 139.22/x
  3. Step 3: Cross multiply
    427.78x = 641.77 × 139.22
  4. Step 4: Simplify right side
    427.78x = 89,346.85
  5. Step 5: Solve for x
    x = 89,346.85/427.78
  6. Step 6: Final answer
    x = 208.86

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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.