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Finding the Fourth Proportional to 209.76, 289.40 and 122.42

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Solution

The fourth proportional to 209.76, 289.40 and 122.42 is: 168.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.76 : 289.40 = 122.42 : x
  2. Step 2: Convert to fraction form
    209.76/289.40 = 122.42/x
  3. Step 3: Cross multiply
    209.76x = 289.40 × 122.42
  4. Step 4: Simplify right side
    209.76x = 35,426.29
  5. Step 5: Solve for x
    x = 35,426.29/209.76
  6. Step 6: Final answer
    x = 168.89

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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.