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Finding the Fourth Proportional to 861.11, 1,291.67 and 211.85

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Solution

The fourth proportional to 861.11, 1,291.67 and 211.85 is: 317.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.11 : 1,291.67 = 211.85 : x
  2. Step 2: Convert to fraction form
    861.11/1,291.67 = 211.85/x
  3. Step 3: Cross multiply
    861.11x = 1,291.67 × 211.85
  4. Step 4: Simplify right side
    861.11x = 273,640.29
  5. Step 5: Solve for x
    x = 273,640.29/861.11
  6. Step 6: Final answer
    x = 317.78

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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.