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Finding the Fourth Proportional to 221.81, 306.08 and 128.55

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Solution

The fourth proportional to 221.81, 306.08 and 128.55 is: 177.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.81 : 306.08 = 128.55 : x
  2. Step 2: Convert to fraction form
    221.81/306.08 = 128.55/x
  3. Step 3: Cross multiply
    221.81x = 306.08 × 128.55
  4. Step 4: Simplify right side
    221.81x = 39,345.37
  5. Step 5: Solve for x
    x = 39,345.37/221.81
  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.