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Finding the Fourth Proportional to 861.56, 1,283.78 and 819.72

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Solution

The fourth proportional to 861.56, 1,283.78 and 819.72 is: 1,221.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.56 : 1,283.78 = 819.72 : x
  2. Step 2: Convert to fraction form
    861.56/1,283.78 = 819.72/x
  3. Step 3: Cross multiply
    861.56x = 1,283.78 × 819.72
  4. Step 4: Simplify right side
    861.56x = 1,052,329.62
  5. Step 5: Solve for x
    x = 1,052,329.62/861.56
  6. Step 6: Final answer
    x = 1,221.43

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.