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Finding the Fourth Proportional to 217.72, 326.40 and 85.96

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Solution

The fourth proportional to 217.72, 326.40 and 85.96 is: 128.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    217.72 : 326.40 = 85.96 : x
  2. Step 2: Convert to fraction form
    217.72/326.40 = 85.96/x
  3. Step 3: Cross multiply
    217.72x = 326.40 × 85.96
  4. Step 4: Simplify right side
    217.72x = 28,057.34
  5. Step 5: Solve for x
    x = 28,057.34/217.72
  6. Step 6: Final answer
    x = 128.87

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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.