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Finding the Fourth Proportional to 211.72, 292.20 and 128.85

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Solution

The fourth proportional to 211.72, 292.20 and 128.85 is: 177.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.72 : 292.20 = 128.85 : x
  2. Step 2: Convert to fraction form
    211.72/292.20 = 128.85/x
  3. Step 3: Cross multiply
    211.72x = 292.20 × 128.85
  4. Step 4: Simplify right side
    211.72x = 37,649.97
  5. Step 5: Solve for x
    x = 37,649.97/211.72
  6. Step 6: Final answer
    x = 177.83

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.