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Finding the Fourth Proportional to 122.74, 169.40 and 79.21

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Solution

The fourth proportional to 122.74, 169.40 and 79.21 is: 109.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.74 : 169.40 = 79.21 : x
  2. Step 2: Convert to fraction form
    122.74/169.40 = 79.21/x
  3. Step 3: Cross multiply
    122.74x = 169.40 × 79.21
  4. Step 4: Simplify right side
    122.74x = 13,417.94
  5. Step 5: Solve for x
    x = 13,417.94/122.74
  6. Step 6: Final answer
    x = 109.32

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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.