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Finding the Fourth Proportional to 89.78, 135.27 and 81.23

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Solution

The fourth proportional to 89.78, 135.27 and 81.23 is: 122.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.78 : 135.27 = 81.23 : x
  2. Step 2: Convert to fraction form
    89.78/135.27 = 81.23/x
  3. Step 3: Cross multiply
    89.78x = 135.27 × 81.23
  4. Step 4: Simplify right side
    89.78x = 10,987.98
  5. Step 5: Solve for x
    x = 10,987.98/89.78
  6. Step 6: Final answer
    x = 122.39

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.