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Finding the Fourth Proportional to 209.86, 289.60 and 121.36

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Solution

The fourth proportional to 209.86, 289.60 and 121.36 is: 167.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.86 : 289.60 = 121.36 : x
  2. Step 2: Convert to fraction form
    209.86/289.60 = 121.36/x
  3. Step 3: Cross multiply
    209.86x = 289.60 × 121.36
  4. Step 4: Simplify right side
    209.86x = 35,145.86
  5. Step 5: Solve for x
    x = 35,145.86/209.86
  6. Step 6: Final answer
    x = 167.47

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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.