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Finding the Fourth Proportional to 861.97, 1,189.82 and 638.71

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Solution

The fourth proportional to 861.97, 1,189.82 and 638.71 is: 881.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.97 : 1,189.82 = 638.71 : x
  2. Step 2: Convert to fraction form
    861.97/1,189.82 = 638.71/x
  3. Step 3: Cross multiply
    861.97x = 1,189.82 × 638.71
  4. Step 4: Simplify right side
    861.97x = 759,949.93
  5. Step 5: Solve for x
    x = 759,949.93/861.97
  6. Step 6: Final answer
    x = 881.64

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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.