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Finding the Fourth Proportional to 221.82, 306.11 and 128.57

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Solution

The fourth proportional to 221.82, 306.11 and 128.57 is: 177.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.82 : 306.11 = 128.57 : x
  2. Step 2: Convert to fraction form
    221.82/306.11 = 128.57/x
  3. Step 3: Cross multiply
    221.82x = 306.11 × 128.57
  4. Step 4: Simplify right side
    221.82x = 39,357.65
  5. Step 5: Solve for x
    x = 39,357.65/221.82
  6. Step 6: Final answer
    x = 177.43

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.