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Finding the Fourth Proportional to 221.38, 305.55 and 128.11

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Solution

The fourth proportional to 221.38, 305.55 and 128.11 is: 176.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.38 : 305.55 = 128.11 : x
  2. Step 2: Convert to fraction form
    221.38/305.55 = 128.11/x
  3. Step 3: Cross multiply
    221.38x = 305.55 × 128.11
  4. Step 4: Simplify right side
    221.38x = 39,143.91
  5. Step 5: Solve for x
    x = 39,143.91/221.38
  6. Step 6: Final answer
    x = 176.82

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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.