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Finding the Fourth Proportional to 81.25, 121.75 and 42.70

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Solution

The fourth proportional to 81.25, 121.75 and 42.70 is: 63.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.25 : 121.75 = 42.70 : x
  2. Step 2: Convert to fraction form
    81.25/121.75 = 42.70/x
  3. Step 3: Cross multiply
    81.25x = 121.75 × 42.70
  4. Step 4: Simplify right side
    81.25x = 5,198.73
  5. Step 5: Solve for x
    x = 5,198.73/81.25
  6. Step 6: Final answer
    x = 63.98

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.