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Finding the Fourth Proportional to 221.78, 306.08 and 128.49

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Solution

The fourth proportional to 221.78, 306.08 and 128.49 is: 177.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.78 : 306.08 = 128.49 : x
  2. Step 2: Convert to fraction form
    221.78/306.08 = 128.49/x
  3. Step 3: Cross multiply
    221.78x = 306.08 × 128.49
  4. Step 4: Simplify right side
    221.78x = 39,327.58
  5. Step 5: Solve for x
    x = 39,327.58/221.78
  6. Step 6: Final answer
    x = 177.33

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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.