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Finding the Fourth Proportional to 221.49, 305.72 and 128.25

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Solution

The fourth proportional to 221.49, 305.72 and 128.25 is: 177.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.49 : 305.72 = 128.25 : x
  2. Step 2: Convert to fraction form
    221.49/305.72 = 128.25/x
  3. Step 3: Cross multiply
    221.49x = 305.72 × 128.25
  4. Step 4: Simplify right side
    221.49x = 39,207.95
  5. Step 5: Solve for x
    x = 39,207.95/221.49
  6. Step 6: Final answer
    x = 177.02

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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.