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Finding the Fourth Proportional to 427.86, 641.70 and 139.29

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Solution

The fourth proportional to 427.86, 641.70 and 139.29 is: 208.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.86 : 641.70 = 139.29 : x
  2. Step 2: Convert to fraction form
    427.86/641.70 = 139.29/x
  3. Step 3: Cross multiply
    427.86x = 641.70 × 139.29
  4. Step 4: Simplify right side
    427.86x = 89,382.39
  5. Step 5: Solve for x
    x = 89,382.39/427.86
  6. Step 6: Final answer
    x = 208.91

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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.