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Finding the Fourth Proportional to 221.88, 306.15 and 128.60

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Solution

The fourth proportional to 221.88, 306.15 and 128.60 is: 177.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.88 : 306.15 = 128.60 : x
  2. Step 2: Convert to fraction form
    221.88/306.15 = 128.60/x
  3. Step 3: Cross multiply
    221.88x = 306.15 × 128.60
  4. Step 4: Simplify right side
    221.88x = 39,369.36
  5. Step 5: Solve for x
    x = 39,369.36/221.88
  6. Step 6: Final answer
    x = 177.44

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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.