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Finding the Fourth Proportional to 101.28, 139.85 and 80.70

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Solution

The fourth proportional to 101.28, 139.85 and 80.70 is: 111.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    101.28 : 139.85 = 80.70 : x
  2. Step 2: Convert to fraction form
    101.28/139.85 = 80.70/x
  3. Step 3: Cross multiply
    101.28x = 139.85 × 80.70
  4. Step 4: Simplify right side
    101.28x = 11,285.90
  5. Step 5: Solve for x
    x = 11,285.90/101.28
  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.