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Finding the Fourth Proportional to 213.57, 320.31 and 91.80

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Solution

The fourth proportional to 213.57, 320.31 and 91.80 is: 137.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.57 : 320.31 = 91.80 : x
  2. Step 2: Convert to fraction form
    213.57/320.31 = 91.80/x
  3. Step 3: Cross multiply
    213.57x = 320.31 × 91.80
  4. Step 4: Simplify right side
    213.57x = 29,404.46
  5. Step 5: Solve for x
    x = 29,404.46/213.57
  6. Step 6: Final answer
    x = 137.68

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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.