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Finding the Fourth Proportional to 209.79, 289.40 and 122.40

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Solution

The fourth proportional to 209.79, 289.40 and 122.40 is: 168.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.79 : 289.40 = 122.40 : x
  2. Step 2: Convert to fraction form
    209.79/289.40 = 122.40/x
  3. Step 3: Cross multiply
    209.79x = 289.40 × 122.40
  4. Step 4: Simplify right side
    209.79x = 35,421.95
  5. Step 5: Solve for x
    x = 35,421.95/209.79
  6. Step 6: Final answer
    x = 168.84

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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.