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Finding the Fourth Proportional to 427.34, 640.96 and 138.78

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Solution

The fourth proportional to 427.34, 640.96 and 138.78 is: 208.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.34 : 640.96 = 138.78 : x
  2. Step 2: Convert to fraction form
    427.34/640.96 = 138.78/x
  3. Step 3: Cross multiply
    427.34x = 640.96 × 138.78
  4. Step 4: Simplify right side
    427.34x = 88,952.43
  5. Step 5: Solve for x
    x = 88,952.43/427.34
  6. Step 6: Final answer
    x = 208.15

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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.