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Finding the Fourth Proportional to 861.81, 1,289.55 and 515.31

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Solution

The fourth proportional to 861.81, 1,289.55 and 515.31 is: 771.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.81 : 1,289.55 = 515.31 : x
  2. Step 2: Convert to fraction form
    861.81/1,289.55 = 515.31/x
  3. Step 3: Cross multiply
    861.81x = 1,289.55 × 515.31
  4. Step 4: Simplify right side
    861.81x = 664,518.01
  5. Step 5: Solve for x
    x = 664,518.01/861.81
  6. Step 6: Final answer
    x = 771.07

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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.