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Finding the Fourth Proportional to 122.64, 169.17 and 81.20

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Solution

The fourth proportional to 122.64, 169.17 and 81.20 is: 112.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.64 : 169.17 = 81.20 : x
  2. Step 2: Convert to fraction form
    122.64/169.17 = 81.20/x
  3. Step 3: Cross multiply
    122.64x = 169.17 × 81.20
  4. Step 4: Simplify right side
    122.64x = 13,735.76
  5. Step 5: Solve for x
    x = 13,735.76/122.64
  6. Step 6: Final answer
    x = 112.00

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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.