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Finding the Fourth Proportional to 139.80, 192.90 and 80.76

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Solution

The fourth proportional to 139.80, 192.90 and 80.76 is: 111.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.80 : 192.90 = 80.76 : x
  2. Step 2: Convert to fraction form
    139.80/192.90 = 80.76/x
  3. Step 3: Cross multiply
    139.80x = 192.90 × 80.76
  4. Step 4: Simplify right side
    139.80x = 15,578.60
  5. Step 5: Solve for x
    x = 15,578.60/139.80
  6. Step 6: Final answer
    x = 111.43

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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.