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Finding the Fourth Proportional to 861.69, 1,291.80 and 399.23

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Solution

The fourth proportional to 861.69, 1,291.80 and 399.23 is: 598.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.69 : 1,291.80 = 399.23 : x
  2. Step 2: Convert to fraction form
    861.69/1,291.80 = 399.23/x
  3. Step 3: Cross multiply
    861.69x = 1,291.80 × 399.23
  4. Step 4: Simplify right side
    861.69x = 515,722.95
  5. Step 5: Solve for x
    x = 515,722.95/861.69
  6. Step 6: Final answer
    x = 598.50

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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.