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Finding the Fourth Proportional to 81.22, 121.22 and 79

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Solution

The fourth proportional to 81.22, 121.22 and 79 is: 117.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.22 : 121.22 = 79 : x
  2. Step 2: Convert to fraction form
    81.22/121.22 = 79/x
  3. Step 3: Cross multiply
    81.22x = 121.22 × 79
  4. Step 4: Simplify right side
    81.22x = 9,576.38
  5. Step 5: Solve for x
    x = 9,576.38/81.22
  6. Step 6: Final answer
    x = 117.91

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.