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Finding the Fourth Proportional to 221.63, 305.85 and 128.39

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Solution

The fourth proportional to 221.63, 305.85 and 128.39 is: 177.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.63 : 305.85 = 128.39 : x
  2. Step 2: Convert to fraction form
    221.63/305.85 = 128.39/x
  3. Step 3: Cross multiply
    221.63x = 305.85 × 128.39
  4. Step 4: Simplify right side
    221.63x = 39,266.55
  5. Step 5: Solve for x
    x = 39,266.55/221.63
  6. Step 6: Final answer
    x = 177.18

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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.