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Finding the Fourth Proportional to 211.86, 317.73 and 81.85

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Solution

The fourth proportional to 211.86, 317.73 and 81.85 is: 122.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.86 : 317.73 = 81.85 : x
  2. Step 2: Convert to fraction form
    211.86/317.73 = 81.85/x
  3. Step 3: Cross multiply
    211.86x = 317.73 × 81.85
  4. Step 4: Simplify right side
    211.86x = 26,005.79
  5. Step 5: Solve for x
    x = 26,005.79/211.86
  6. Step 6: Final answer
    x = 122.75

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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.