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Finding the Fourth Proportional to 215.78, 323.70 and 85.71

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Solution

The fourth proportional to 215.78, 323.70 and 85.71 is: 128.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    215.78 : 323.70 = 85.71 : x
  2. Step 2: Convert to fraction form
    215.78/323.70 = 85.71/x
  3. Step 3: Cross multiply
    215.78x = 323.70 × 85.71
  4. Step 4: Simplify right side
    215.78x = 27,743.90
  5. Step 5: Solve for x
    x = 27,743.90/215.78
  6. Step 6: Final answer
    x = 128.58

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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.