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Finding the Fourth Proportional to 213.55, 320.39 and 91.85

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Solution

The fourth proportional to 213.55, 320.39 and 91.85 is: 137.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.55 : 320.39 = 91.85 : x
  2. Step 2: Convert to fraction form
    213.55/320.39 = 91.85/x
  3. Step 3: Cross multiply
    213.55x = 320.39 × 91.85
  4. Step 4: Simplify right side
    213.55x = 29,427.25
  5. Step 5: Solve for x
    x = 29,427.25/213.55
  6. Step 6: Final answer
    x = 137.80

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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.