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Finding the Fourth Proportional to 139.54, 209.12 and 78.62

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Solution

The fourth proportional to 139.54, 209.12 and 78.62 is: 117.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.54 : 209.12 = 78.62 : x
  2. Step 2: Convert to fraction form
    139.54/209.12 = 78.62/x
  3. Step 3: Cross multiply
    139.54x = 209.12 × 78.62
  4. Step 4: Simplify right side
    139.54x = 16,441.01
  5. Step 5: Solve for x
    x = 16,441.01/139.54
  6. Step 6: Final answer
    x = 117.82

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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.