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Finding the Fourth Proportional to 139.66, 192.78 and 81.46

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Solution

The fourth proportional to 139.66, 192.78 and 81.46 is: 112.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.66 : 192.78 = 81.46 : x
  2. Step 2: Convert to fraction form
    139.66/192.78 = 81.46/x
  3. Step 3: Cross multiply
    139.66x = 192.78 × 81.46
  4. Step 4: Simplify right side
    139.66x = 15,702.79
  5. Step 5: Solve for x
    x = 15,702.79/139.66
  6. Step 6: Final answer
    x = 112.43

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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.