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Finding the Fourth Proportional to 139.62, 192.68 and 81.40

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Solution

The fourth proportional to 139.62, 192.68 and 81.40 is: 112.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.62 : 192.68 = 81.40 : x
  2. Step 2: Convert to fraction form
    139.62/192.68 = 81.40/x
  3. Step 3: Cross multiply
    139.62x = 192.68 × 81.40
  4. Step 4: Simplify right side
    139.62x = 15,684.15
  5. Step 5: Solve for x
    x = 15,684.15/139.62
  6. Step 6: Final answer
    x = 112.33

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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.