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Finding the Fourth Proportional to 139.89, 209.66 and 71.31

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Solution

The fourth proportional to 139.89, 209.66 and 71.31 is: 106.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.89 : 209.66 = 71.31 : x
  2. Step 2: Convert to fraction form
    139.89/209.66 = 71.31/x
  3. Step 3: Cross multiply
    139.89x = 209.66 × 71.31
  4. Step 4: Simplify right side
    139.89x = 14,950.85
  5. Step 5: Solve for x
    x = 14,950.85/139.89
  6. Step 6: Final answer
    x = 106.88

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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.