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Finding the Fourth Proportional to 427.56, 641.38 and 139

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Solution

The fourth proportional to 427.56, 641.38 and 139 is: 208.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.56 : 641.38 = 139 : x
  2. Step 2: Convert to fraction form
    427.56/641.38 = 139/x
  3. Step 3: Cross multiply
    427.56x = 641.38 × 139
  4. Step 4: Simplify right side
    427.56x = 89,151.82
  5. Step 5: Solve for x
    x = 89,151.82/427.56
  6. Step 6: Final answer
    x = 208.51

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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.