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Finding the Fourth Proportional to 139.89, 192.96 and 81.63

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Solution

The fourth proportional to 139.89, 192.96 and 81.63 is: 112.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.89 : 192.96 = 81.63 : x
  2. Step 2: Convert to fraction form
    139.89/192.96 = 81.63/x
  3. Step 3: Cross multiply
    139.89x = 192.96 × 81.63
  4. Step 4: Simplify right side
    139.89x = 15,751.32
  5. Step 5: Solve for x
    x = 15,751.32/139.89
  6. Step 6: Final answer
    x = 112.60

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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.