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Finding the Fourth Proportional to 221.67, 305.91 and 128.43

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Solution

The fourth proportional to 221.67, 305.91 and 128.43 is: 177.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.67 : 305.91 = 128.43 : x
  2. Step 2: Convert to fraction form
    221.67/305.91 = 128.43/x
  3. Step 3: Cross multiply
    221.67x = 305.91 × 128.43
  4. Step 4: Simplify right side
    221.67x = 39,288.02
  5. Step 5: Solve for x
    x = 39,288.02/221.67
  6. Step 6: Final answer
    x = 177.24

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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.