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Finding the Fourth Proportional to 209.43, 313.81 and 128.03

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Solution

The fourth proportional to 209.43, 313.81 and 128.03 is: 191.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.43 : 313.81 = 128.03 : x
  2. Step 2: Convert to fraction form
    209.43/313.81 = 128.03/x
  3. Step 3: Cross multiply
    209.43x = 313.81 × 128.03
  4. Step 4: Simplify right side
    209.43x = 40,175.21
  5. Step 5: Solve for x
    x = 40,175.21/209.43
  6. Step 6: Final answer
    x = 191.83

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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.