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Finding the Fourth Proportional to 209.80, 289.49 and 121.30

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Solution

The fourth proportional to 209.80, 289.49 and 121.30 is: 167.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.80 : 289.49 = 121.30 : x
  2. Step 2: Convert to fraction form
    209.80/289.49 = 121.30/x
  3. Step 3: Cross multiply
    209.80x = 289.49 × 121.30
  4. Step 4: Simplify right side
    209.80x = 35,115.14
  5. Step 5: Solve for x
    x = 35,115.14/209.80
  6. Step 6: Final answer
    x = 167.37

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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.