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Finding the Fourth Proportional to 427.26, 640.96 and 138.72

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Solution

The fourth proportional to 427.26, 640.96 and 138.72 is: 208.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.26 : 640.96 = 138.72 : x
  2. Step 2: Convert to fraction form
    427.26/640.96 = 138.72/x
  3. Step 3: Cross multiply
    427.26x = 640.96 × 138.72
  4. Step 4: Simplify right side
    427.26x = 88,913.97
  5. Step 5: Solve for x
    x = 88,913.97/427.26
  6. Step 6: Final answer
    x = 208.10

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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.