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Finding the Fourth Proportional to 213.91, 320.87 and 85.66

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Solution

The fourth proportional to 213.91, 320.87 and 85.66 is: 128.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.91 : 320.87 = 85.66 : x
  2. Step 2: Convert to fraction form
    213.91/320.87 = 85.66/x
  3. Step 3: Cross multiply
    213.91x = 320.87 × 85.66
  4. Step 4: Simplify right side
    213.91x = 27,485.30
  5. Step 5: Solve for x
    x = 27,485.30/213.91
  6. Step 6: Final answer
    x = 128.49

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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.