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Finding the Fourth Proportional to 101.28, 139.72 and 61.90

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Solution

The fourth proportional to 101.28, 139.72 and 61.90 is: 85.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    101.28 : 139.72 = 61.90 : x
  2. Step 2: Convert to fraction form
    101.28/139.72 = 61.90/x
  3. Step 3: Cross multiply
    101.28x = 139.72 × 61.90
  4. Step 4: Simplify right side
    101.28x = 8,648.67
  5. Step 5: Solve for x
    x = 8,648.67/101.28
  6. Step 6: Final answer
    x = 85.39

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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.