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Finding the Fourth Proportional to 209.97, 314.91 and 128.61

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Solution

The fourth proportional to 209.97, 314.91 and 128.61 is: 192.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.97 : 314.91 = 128.61 : x
  2. Step 2: Convert to fraction form
    209.97/314.91 = 128.61/x
  3. Step 3: Cross multiply
    209.97x = 314.91 × 128.61
  4. Step 4: Simplify right side
    209.97x = 40,500.58
  5. Step 5: Solve for x
    x = 40,500.58/209.97
  6. Step 6: Final answer
    x = 192.89

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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.