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Finding the Fourth Proportional to 324.78, 487.16 and 81.31

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Solution

The fourth proportional to 324.78, 487.16 and 81.31 is: 121.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    324.78 : 487.16 = 81.31 : x
  2. Step 2: Convert to fraction form
    324.78/487.16 = 81.31/x
  3. Step 3: Cross multiply
    324.78x = 487.16 × 81.31
  4. Step 4: Simplify right side
    324.78x = 39,610.98
  5. Step 5: Solve for x
    x = 39,610.98/324.78
  6. Step 6: Final answer
    x = 121.96

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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.