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Finding the Fourth Proportional to 205.92, 308.48 and 128.70

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Solution

The fourth proportional to 205.92, 308.48 and 128.70 is: 192.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    205.92 : 308.48 = 128.70 : x
  2. Step 2: Convert to fraction form
    205.92/308.48 = 128.70/x
  3. Step 3: Cross multiply
    205.92x = 308.48 × 128.70
  4. Step 4: Simplify right side
    205.92x = 39,700.73
  5. Step 5: Solve for x
    x = 39,700.73/205.92
  6. Step 6: Final answer
    x = 192.80

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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.