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Finding the Fourth Proportional to 209.25, 288.80 and 121.91

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Solution

The fourth proportional to 209.25, 288.80 and 121.91 is: 168.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.25 : 288.80 = 121.91 : x
  2. Step 2: Convert to fraction form
    209.25/288.80 = 121.91/x
  3. Step 3: Cross multiply
    209.25x = 288.80 × 121.91
  4. Step 4: Simplify right side
    209.25x = 35,206.01
  5. Step 5: Solve for x
    x = 35,206.01/209.25
  6. Step 6: Final answer
    x = 168.25

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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.