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Finding the Fourth Proportional to 81.26, 121.05 and 78.29

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Solution

The fourth proportional to 81.26, 121.05 and 78.29 is: 116.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.26 : 121.05 = 78.29 : x
  2. Step 2: Convert to fraction form
    81.26/121.05 = 78.29/x
  3. Step 3: Cross multiply
    81.26x = 121.05 × 78.29
  4. Step 4: Simplify right side
    81.26x = 9,476.61
  5. Step 5: Solve for x
    x = 9,476.61/81.26
  6. Step 6: Final answer
    x = 116.62

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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.