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Finding the Fourth Proportional to 221.72, 305.98 and 128.46

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Solution

The fourth proportional to 221.72, 305.98 and 128.46 is: 177.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.72 : 305.98 = 128.46 : x
  2. Step 2: Convert to fraction form
    221.72/305.98 = 128.46/x
  3. Step 3: Cross multiply
    221.72x = 305.98 × 128.46
  4. Step 4: Simplify right side
    221.72x = 39,306.19
  5. Step 5: Solve for x
    x = 39,306.19/221.72
  6. Step 6: Final answer
    x = 177.28

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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.