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Finding the Fourth Proportional to 209.20, 288.69 and 121.87

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Solution

The fourth proportional to 209.20, 288.69 and 121.87 is: 168.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.20 : 288.69 = 121.87 : x
  2. Step 2: Convert to fraction form
    209.20/288.69 = 121.87/x
  3. Step 3: Cross multiply
    209.20x = 288.69 × 121.87
  4. Step 4: Simplify right side
    209.20x = 35,182.65
  5. Step 5: Solve for x
    x = 35,182.65/209.20
  6. Step 6: Final answer
    x = 168.18

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.