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Finding the Fourth Proportional to 205.86, 309.20 and 128.96

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Solution

The fourth proportional to 205.86, 309.20 and 128.96 is: 193.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    205.86 : 309.20 = 128.96 : x
  2. Step 2: Convert to fraction form
    205.86/309.20 = 128.96/x
  3. Step 3: Cross multiply
    205.86x = 309.20 × 128.96
  4. Step 4: Simplify right side
    205.86x = 39,874.43
  5. Step 5: Solve for x
    x = 39,874.43/205.86
  6. Step 6: Final answer
    x = 193.70

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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.