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Finding the Fourth Proportional to 219.75, 329.21 and 128.42

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Solution

The fourth proportional to 219.75, 329.21 and 128.42 is: 192.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    219.75 : 329.21 = 128.42 : x
  2. Step 2: Convert to fraction form
    219.75/329.21 = 128.42/x
  3. Step 3: Cross multiply
    219.75x = 329.21 × 128.42
  4. Step 4: Simplify right side
    219.75x = 42,277.15
  5. Step 5: Solve for x
    x = 42,277.15/219.75
  6. Step 6: Final answer
    x = 192.39

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.