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Finding the Fourth Proportional to 209.11, 288.51 and 121.72

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Solution

The fourth proportional to 209.11, 288.51 and 121.72 is: 167.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.11 : 288.51 = 121.72 : x
  2. Step 2: Convert to fraction form
    209.11/288.51 = 121.72/x
  3. Step 3: Cross multiply
    209.11x = 288.51 × 121.72
  4. Step 4: Simplify right side
    209.11x = 35,115.99
  5. Step 5: Solve for x
    x = 35,115.99/209.11
  6. Step 6: Final answer
    x = 167.93

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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.