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Finding the Fourth Proportional to 427.63, 641.31 and 139

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Solution

The fourth proportional to 427.63, 641.31 and 139 is: 208.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.63 : 641.31 = 139 : x
  2. Step 2: Convert to fraction form
    427.63/641.31 = 139/x
  3. Step 3: Cross multiply
    427.63x = 641.31 × 139
  4. Step 4: Simplify right side
    427.63x = 89,142.09
  5. Step 5: Solve for x
    x = 89,142.09/427.63
  6. Step 6: Final answer
    x = 208.46

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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.