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Finding the Fourth Proportional to 861.29, 1,289.64 and 686.79

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Solution

The fourth proportional to 861.29, 1,289.64 and 686.79 is: 1,028.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.29 : 1,289.64 = 686.79 : x
  2. Step 2: Convert to fraction form
    861.29/1,289.64 = 686.79/x
  3. Step 3: Cross multiply
    861.29x = 1,289.64 × 686.79
  4. Step 4: Simplify right side
    861.29x = 885,711.86
  5. Step 5: Solve for x
    x = 885,711.86/861.29
  6. Step 6: Final answer
    x = 1,028.36

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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.