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Finding the Fourth Proportional to 861.76, 1,291.56 and 399.52

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Solution

The fourth proportional to 861.76, 1,291.56 and 399.52 is: 598.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.76 : 1,291.56 = 399.52 : x
  2. Step 2: Convert to fraction form
    861.76/1,291.56 = 399.52/x
  3. Step 3: Cross multiply
    861.76x = 1,291.56 × 399.52
  4. Step 4: Simplify right side
    861.76x = 516,004.05
  5. Step 5: Solve for x
    x = 516,004.05/861.76
  6. Step 6: Final answer
    x = 598.78

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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.