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Finding the Fourth Proportional to 209.16, 288.60 and 121.78

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Solution

The fourth proportional to 209.16, 288.60 and 121.78 is: 168.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.16 : 288.60 = 121.78 : x
  2. Step 2: Convert to fraction form
    209.16/288.60 = 121.78/x
  3. Step 3: Cross multiply
    209.16x = 288.60 × 121.78
  4. Step 4: Simplify right side
    209.16x = 35,145.61
  5. Step 5: Solve for x
    x = 35,145.61/209.16
  6. Step 6: Final answer
    x = 168.03

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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.