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Finding the Fourth Proportional to 122.70, 169.40 and 81.24

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Solution

The fourth proportional to 122.70, 169.40 and 81.24 is: 112.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.70 : 169.40 = 81.24 : x
  2. Step 2: Convert to fraction form
    122.70/169.40 = 81.24/x
  3. Step 3: Cross multiply
    122.70x = 169.40 × 81.24
  4. Step 4: Simplify right side
    122.70x = 13,761.65
  5. Step 5: Solve for x
    x = 13,761.65/122.70
  6. Step 6: Final answer
    x = 112.16

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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.