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Finding the Fourth Proportional to 427.87, 641.80 and 139.30

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Solution

The fourth proportional to 427.87, 641.80 and 139.30 is: 208.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.87 : 641.80 = 139.30 : x
  2. Step 2: Convert to fraction form
    427.87/641.80 = 139.30/x
  3. Step 3: Cross multiply
    427.87x = 641.80 × 139.30
  4. Step 4: Simplify right side
    427.87x = 89,402.74
  5. Step 5: Solve for x
    x = 89,402.74/427.87
  6. Step 6: Final answer
    x = 208.95

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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.