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Finding the Fourth Proportional to 139.74, 192.85 and 81.50

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Solution

The fourth proportional to 139.74, 192.85 and 81.50 is: 112.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.74 : 192.85 = 81.50 : x
  2. Step 2: Convert to fraction form
    139.74/192.85 = 81.50/x
  3. Step 3: Cross multiply
    139.74x = 192.85 × 81.50
  4. Step 4: Simplify right side
    139.74x = 15,717.28
  5. Step 5: Solve for x
    x = 15,717.28/139.74
  6. Step 6: Final answer
    x = 112.48

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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.