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Finding the Fourth Proportional to 139.68, 192.69 and 81.45

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Solution

The fourth proportional to 139.68, 192.69 and 81.45 is: 112.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.68 : 192.69 = 81.45 : x
  2. Step 2: Convert to fraction form
    139.68/192.69 = 81.45/x
  3. Step 3: Cross multiply
    139.68x = 192.69 × 81.45
  4. Step 4: Simplify right side
    139.68x = 15,694.60
  5. Step 5: Solve for x
    x = 15,694.60/139.68
  6. Step 6: Final answer
    x = 112.36

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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.