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Finding the Fourth Proportional to 81.22, 121.54 and 75.79

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Solution

The fourth proportional to 81.22, 121.54 and 75.79 is: 113.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.22 : 121.54 = 75.79 : x
  2. Step 2: Convert to fraction form
    81.22/121.54 = 75.79/x
  3. Step 3: Cross multiply
    81.22x = 121.54 × 75.79
  4. Step 4: Simplify right side
    81.22x = 9,210.95
  5. Step 5: Solve for x
    x = 9,210.95/81.22
  6. Step 6: Final answer
    x = 113.41

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.