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Finding the Fourth Proportional to 209, 288.38 and 121.68

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Solution

The fourth proportional to 209, 288.38 and 121.68 is: 167.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    209 : 288.38 = 121.68 : x
  2. Step 2: Convert to fraction form
    209/288.38 = 121.68/x
  3. Step 3: Cross multiply
    209x = 288.38 × 121.68
  4. Step 4: Simplify right side
    209x = 35,090.08
  5. Step 5: Solve for x
    x = 35,090.08/209
  6. Step 6: Final answer
    x = 167.90

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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.