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Finding the Fourth Proportional to 122.61, 169.29 and 78.42

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Solution

The fourth proportional to 122.61, 169.29 and 78.42 is: 108.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.61 : 169.29 = 78.42 : x
  2. Step 2: Convert to fraction form
    122.61/169.29 = 78.42/x
  3. Step 3: Cross multiply
    122.61x = 169.29 × 78.42
  4. Step 4: Simplify right side
    122.61x = 13,275.72
  5. Step 5: Solve for x
    x = 13,275.72/122.61
  6. Step 6: Final answer
    x = 108.28

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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.