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Finding the Fourth Proportional to 139.02, 208.42 and 81.25

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Solution

The fourth proportional to 139.02, 208.42 and 81.25 is: 121.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.02 : 208.42 = 81.25 : x
  2. Step 2: Convert to fraction form
    139.02/208.42 = 81.25/x
  3. Step 3: Cross multiply
    139.02x = 208.42 × 81.25
  4. Step 4: Simplify right side
    139.02x = 16,935.03
  5. Step 5: Solve for x
    x = 16,935.03/139.02
  6. Step 6: Final answer
    x = 121.82

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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.