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Finding the Fourth Proportional to 205.76, 308.71 and 128.78

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Solution

The fourth proportional to 205.76, 308.71 and 128.78 is: 193.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    205.76 : 308.71 = 128.78 : x
  2. Step 2: Convert to fraction form
    205.76/308.71 = 128.78/x
  3. Step 3: Cross multiply
    205.76x = 308.71 × 128.78
  4. Step 4: Simplify right side
    205.76x = 39,753.49
  5. Step 5: Solve for x
    x = 39,753.49/205.76
  6. Step 6: Final answer
    x = 193.21

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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.