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Finding the Fourth Proportional to 221.68, 305.90 and 128.44

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Solution

The fourth proportional to 221.68, 305.90 and 128.44 is: 177.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.68 : 305.90 = 128.44 : x
  2. Step 2: Convert to fraction form
    221.68/305.90 = 128.44/x
  3. Step 3: Cross multiply
    221.68x = 305.90 × 128.44
  4. Step 4: Simplify right side
    221.68x = 39,289.80
  5. Step 5: Solve for x
    x = 39,289.80/221.68
  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.