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Finding the Fourth Proportional to 861.18, 1,291.32 and 398.76

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Solution

The fourth proportional to 861.18, 1,291.32 and 398.76 is: 597.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.18 : 1,291.32 = 398.76 : x
  2. Step 2: Convert to fraction form
    861.18/1,291.32 = 398.76/x
  3. Step 3: Cross multiply
    861.18x = 1,291.32 × 398.76
  4. Step 4: Simplify right side
    861.18x = 514,926.76
  5. Step 5: Solve for x
    x = 514,926.76/861.18
  6. Step 6: Final answer
    x = 597.93

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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.