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Finding the Fourth Proportional to 209.40, 289.08 and 122.16

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Solution

The fourth proportional to 209.40, 289.08 and 122.16 is: 168.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.40 : 289.08 = 122.16 : x
  2. Step 2: Convert to fraction form
    209.40/289.08 = 122.16/x
  3. Step 3: Cross multiply
    209.40x = 289.08 × 122.16
  4. Step 4: Simplify right side
    209.40x = 35,314.01
  5. Step 5: Solve for x
    x = 35,314.01/209.40
  6. Step 6: Final answer
    x = 168.64

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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.