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Finding the Fourth Proportional to 221.78, 306.07 and 128.54

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Solution

The fourth proportional to 221.78, 306.07 and 128.54 is: 177.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.78 : 306.07 = 128.54 : x
  2. Step 2: Convert to fraction form
    221.78/306.07 = 128.54/x
  3. Step 3: Cross multiply
    221.78x = 306.07 × 128.54
  4. Step 4: Simplify right side
    221.78x = 39,342.68
  5. Step 5: Solve for x
    x = 39,342.68/221.78
  6. Step 6: Final answer
    x = 177.39

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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.