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Finding the Fourth Proportional to 81.57, 122.25 and 47.31

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Solution

The fourth proportional to 81.57, 122.25 and 47.31 is: 70.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.57 : 122.25 = 47.31 : x
  2. Step 2: Convert to fraction form
    81.57/122.25 = 47.31/x
  3. Step 3: Cross multiply
    81.57x = 122.25 × 47.31
  4. Step 4: Simplify right side
    81.57x = 5,783.65
  5. Step 5: Solve for x
    x = 5,783.65/81.57
  6. Step 6: Final answer
    x = 70.90

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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.