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Finding the Fourth Proportional to 865.20, 1,297.95 and 318.15

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Solution

The fourth proportional to 865.20, 1,297.95 and 318.15 is: 477.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.20 : 1,297.95 = 318.15 : x
  2. Step 2: Convert to fraction form
    865.20/1,297.95 = 318.15/x
  3. Step 3: Cross multiply
    865.20x = 1,297.95 × 318.15
  4. Step 4: Simplify right side
    865.20x = 412,942.79
  5. Step 5: Solve for x
    x = 412,942.79/865.20
  6. Step 6: Final answer
    x = 477.28

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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.