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Finding the Fourth Proportional to 215.11, 321.87 and 128.49

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Solution

The fourth proportional to 215.11, 321.87 and 128.49 is: 192.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    215.11 : 321.87 = 128.49 : x
  2. Step 2: Convert to fraction form
    215.11/321.87 = 128.49/x
  3. Step 3: Cross multiply
    215.11x = 321.87 × 128.49
  4. Step 4: Simplify right side
    215.11x = 41,356.98
  5. Step 5: Solve for x
    x = 41,356.98/215.11
  6. Step 6: Final answer
    x = 192.26

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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.