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Finding the Fourth Proportional to 139.69, 192.78 and 76.68

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Solution

The fourth proportional to 139.69, 192.78 and 76.68 is: 105.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.69 : 192.78 = 76.68 : x
  2. Step 2: Convert to fraction form
    139.69/192.78 = 76.68/x
  3. Step 3: Cross multiply
    139.69x = 192.78 × 76.68
  4. Step 4: Simplify right side
    139.69x = 14,781.40
  5. Step 5: Solve for x
    x = 14,781.40/139.69
  6. Step 6: Final answer
    x = 105.81

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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.