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Finding the Fourth Proportional to 139.38, 192.36 and 81.18

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Solution

The fourth proportional to 139.38, 192.36 and 81.18 is: 112.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.38 : 192.36 = 81.18 : x
  2. Step 2: Convert to fraction form
    139.38/192.36 = 81.18/x
  3. Step 3: Cross multiply
    139.38x = 192.36 × 81.18
  4. Step 4: Simplify right side
    139.38x = 15,615.78
  5. Step 5: Solve for x
    x = 15,615.78/139.38
  6. Step 6: Final answer
    x = 112.04

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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.