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Finding the Fourth Proportional to 427.17, 640.74 and 138.61

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Solution

The fourth proportional to 427.17, 640.74 and 138.61 is: 207.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.17 : 640.74 = 138.61 : x
  2. Step 2: Convert to fraction form
    427.17/640.74 = 138.61/x
  3. Step 3: Cross multiply
    427.17x = 640.74 × 138.61
  4. Step 4: Simplify right side
    427.17x = 88,809.77
  5. Step 5: Solve for x
    x = 88,809.77/427.17
  6. Step 6: Final answer
    x = 207.90

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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.