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Finding the Fourth Proportional to 100.80, 139.85 and 92.70

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Solution

The fourth proportional to 100.80, 139.85 and 92.70 is: 128.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.80 : 139.85 = 92.70 : x
  2. Step 2: Convert to fraction form
    100.80/139.85 = 92.70/x
  3. Step 3: Cross multiply
    100.80x = 139.85 × 92.70
  4. Step 4: Simplify right side
    100.80x = 12,963.98
  5. Step 5: Solve for x
    x = 12,963.98/100.80
  6. Step 6: Final answer
    x = 128.61

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.