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Finding the Fourth Proportional to 139.46, 208.71 and 85.39

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Solution

The fourth proportional to 139.46, 208.71 and 85.39 is: 127.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.46 : 208.71 = 85.39 : x
  2. Step 2: Convert to fraction form
    139.46/208.71 = 85.39/x
  3. Step 3: Cross multiply
    139.46x = 208.71 × 85.39
  4. Step 4: Simplify right side
    139.46x = 17,821.23
  5. Step 5: Solve for x
    x = 17,821.23/139.46
  6. Step 6: Final answer
    x = 127.79

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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.