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Finding the Fourth Proportional to 427.18, 640.77 and 138.58

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Solution

The fourth proportional to 427.18, 640.77 and 138.58 is: 207.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.18 : 640.77 = 138.58 : x
  2. Step 2: Convert to fraction form
    427.18/640.77 = 138.58/x
  3. Step 3: Cross multiply
    427.18x = 640.77 × 138.58
  4. Step 4: Simplify right side
    427.18x = 88,797.91
  5. Step 5: Solve for x
    x = 88,797.91/427.18
  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.