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Finding the Fourth Proportional to 865.12, 1,297.66 and 215.86

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Solution

The fourth proportional to 865.12, 1,297.66 and 215.86 is: 323.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.12 : 1,297.66 = 215.86 : x
  2. Step 2: Convert to fraction form
    865.12/1,297.66 = 215.86/x
  3. Step 3: Cross multiply
    865.12x = 1,297.66 × 215.86
  4. Step 4: Simplify right side
    865.12x = 280,112.89
  5. Step 5: Solve for x
    x = 280,112.89/865.12
  6. Step 6: Final answer
    x = 323.79

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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.