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Finding the Fourth Proportional to 861.14, 1,290 and 398.28

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Solution

The fourth proportional to 861.14, 1,290 and 398.28 is: 596.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.14 : 1,290 = 398.28 : x
  2. Step 2: Convert to fraction form
    861.14/1,290 = 398.28/x
  3. Step 3: Cross multiply
    861.14x = 1,290 × 398.28
  4. Step 4: Simplify right side
    861.14x = 513,781.20
  5. Step 5: Solve for x
    x = 513,781.20/861.14
  6. Step 6: Final answer
    x = 596.63

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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.