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Finding the Fourth Proportional to 205.86, 309.12 and 128.98

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Solution

The fourth proportional to 205.86, 309.12 and 128.98 is: 193.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    205.86 : 309.12 = 128.98 : x
  2. Step 2: Convert to fraction form
    205.86/309.12 = 128.98/x
  3. Step 3: Cross multiply
    205.86x = 309.12 × 128.98
  4. Step 4: Simplify right side
    205.86x = 39,870.30
  5. Step 5: Solve for x
    x = 39,870.30/205.86
  6. Step 6: Final answer
    x = 193.68

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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.