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Finding the Fourth Proportional to 122.20, 168.68 and 78.55

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Solution

The fourth proportional to 122.20, 168.68 and 78.55 is: 108.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.20 : 168.68 = 78.55 : x
  2. Step 2: Convert to fraction form
    122.20/168.68 = 78.55/x
  3. Step 3: Cross multiply
    122.20x = 168.68 × 78.55
  4. Step 4: Simplify right side
    122.20x = 13,249.81
  5. Step 5: Solve for x
    x = 13,249.81/122.20
  6. Step 6: Final answer
    x = 108.43

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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.