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Finding the Fourth Proportional to 861.48, 1,290.49 and 398.61

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Solution

The fourth proportional to 861.48, 1,290.49 and 398.61 is: 597.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.48 : 1,290.49 = 398.61 : x
  2. Step 2: Convert to fraction form
    861.48/1,290.49 = 398.61/x
  3. Step 3: Cross multiply
    861.48x = 1,290.49 × 398.61
  4. Step 4: Simplify right side
    861.48x = 514,402.22
  5. Step 5: Solve for x
    x = 514,402.22/861.48
  6. Step 6: Final answer
    x = 597.11

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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.