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Finding the Fourth Proportional to 427.81, 641.75 and 139.26

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Solution

The fourth proportional to 427.81, 641.75 and 139.26 is: 208.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.81 : 641.75 = 139.26 : x
  2. Step 2: Convert to fraction form
    427.81/641.75 = 139.26/x
  3. Step 3: Cross multiply
    427.81x = 641.75 × 139.26
  4. Step 4: Simplify right side
    427.81x = 89,370.11
  5. Step 5: Solve for x
    x = 89,370.11/427.81
  6. Step 6: Final answer
    x = 208.90

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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.