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Finding the Fourth Proportional to 207.78, 311.96 and 139.42

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Solution

The fourth proportional to 207.78, 311.96 and 139.42 is: 209.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    207.78 : 311.96 = 139.42 : x
  2. Step 2: Convert to fraction form
    207.78/311.96 = 139.42/x
  3. Step 3: Cross multiply
    207.78x = 311.96 × 139.42
  4. Step 4: Simplify right side
    207.78x = 43,493.46
  5. Step 5: Solve for x
    x = 43,493.46/207.78
  6. Step 6: Final answer
    x = 209.32

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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.