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Finding the Fourth Proportional to 139.84, 207.92 and 138.40

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Solution

The fourth proportional to 139.84, 207.92 and 138.40 is: 205.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.84 : 207.92 = 138.40 : x
  2. Step 2: Convert to fraction form
    139.84/207.92 = 138.40/x
  3. Step 3: Cross multiply
    139.84x = 207.92 × 138.40
  4. Step 4: Simplify right side
    139.84x = 28,776.13
  5. Step 5: Solve for x
    x = 28,776.13/139.84
  6. Step 6: Final answer
    x = 205.78

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.