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Finding the Fourth Proportional to 427.72, 641.66 and 139.12

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Solution

The fourth proportional to 427.72, 641.66 and 139.12 is: 208.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.72 : 641.66 = 139.12 : x
  2. Step 2: Convert to fraction form
    427.72/641.66 = 139.12/x
  3. Step 3: Cross multiply
    427.72x = 641.66 × 139.12
  4. Step 4: Simplify right side
    427.72x = 89,267.74
  5. Step 5: Solve for x
    x = 89,267.74/427.72
  6. Step 6: Final answer
    x = 208.71

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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.