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Finding the Fourth Proportional to 139.23, 192.13 and 81

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Solution

The fourth proportional to 139.23, 192.13 and 81 is: 111.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.23 : 192.13 = 81 : x
  2. Step 2: Convert to fraction form
    139.23/192.13 = 81/x
  3. Step 3: Cross multiply
    139.23x = 192.13 × 81
  4. Step 4: Simplify right side
    139.23x = 15,562.33
  5. Step 5: Solve for x
    x = 15,562.33/139.23
  6. Step 6: Final answer
    x = 111.77

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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.