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Finding the Fourth Proportional to 139.54, 192.56 and 81.31

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Solution

The fourth proportional to 139.54, 192.56 and 81.31 is: 112.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.54 : 192.56 = 81.31 : x
  2. Step 2: Convert to fraction form
    139.54/192.56 = 81.31/x
  3. Step 3: Cross multiply
    139.54x = 192.56 × 81.31
  4. Step 4: Simplify right side
    139.54x = 15,657.05
  5. Step 5: Solve for x
    x = 15,657.05/139.54
  6. Step 6: Final answer
    x = 112.20

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.