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Finding the Fourth Proportional to 427.15, 640.81 and 138.56

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Solution

The fourth proportional to 427.15, 640.81 and 138.56 is: 207.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.15 : 640.81 = 138.56 : x
  2. Step 2: Convert to fraction form
    427.15/640.81 = 138.56/x
  3. Step 3: Cross multiply
    427.15x = 640.81 × 138.56
  4. Step 4: Simplify right side
    427.15x = 88,792.41
  5. Step 5: Solve for x
    x = 88,792.41/427.15
  6. Step 6: Final answer
    x = 207.87

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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.