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Finding the Fourth Proportional to 427.09, 640.74 and 138.53

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Solution

The fourth proportional to 427.09, 640.74 and 138.53 is: 207.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.09 : 640.74 = 138.53 : x
  2. Step 2: Convert to fraction form
    427.09/640.74 = 138.53/x
  3. Step 3: Cross multiply
    427.09x = 640.74 × 138.53
  4. Step 4: Simplify right side
    427.09x = 88,761.71
  5. Step 5: Solve for x
    x = 88,761.71/427.09
  6. Step 6: Final answer
    x = 207.83

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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.