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Finding the Fourth Proportional to 427.42, 640.68 and 138.76

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Solution

The fourth proportional to 427.42, 640.68 and 138.76 is: 207.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.42 : 640.68 = 138.76 : x
  2. Step 2: Convert to fraction form
    427.42/640.68 = 138.76/x
  3. Step 3: Cross multiply
    427.42x = 640.68 × 138.76
  4. Step 4: Simplify right side
    427.42x = 88,900.76
  5. Step 5: Solve for x
    x = 88,900.76/427.42
  6. Step 6: Final answer
    x = 207.99

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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.