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Finding the Fourth Proportional to 209.76, 289.47 and 121.21

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Solution

The fourth proportional to 209.76, 289.47 and 121.21 is: 167.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.76 : 289.47 = 121.21 : x
  2. Step 2: Convert to fraction form
    209.76/289.47 = 121.21/x
  3. Step 3: Cross multiply
    209.76x = 289.47 × 121.21
  4. Step 4: Simplify right side
    209.76x = 35,086.66
  5. Step 5: Solve for x
    x = 35,086.66/209.76
  6. Step 6: Final answer
    x = 167.27

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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.