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Finding the Fourth Proportional to 861.05, 1,291.57 and 211.79

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Solution

The fourth proportional to 861.05, 1,291.57 and 211.79 is: 317.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.05 : 1,291.57 = 211.79 : x
  2. Step 2: Convert to fraction form
    861.05/1,291.57 = 211.79/x
  3. Step 3: Cross multiply
    861.05x = 1,291.57 × 211.79
  4. Step 4: Simplify right side
    861.05x = 273,544.31
  5. Step 5: Solve for x
    x = 273,544.31/861.05
  6. Step 6: Final answer
    x = 317.69

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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.