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Finding the Fourth Proportional to 85.23, 128.01 and 81.39

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Solution

The fourth proportional to 85.23, 128.01 and 81.39 is: 122.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.23 : 128.01 = 81.39 : x
  2. Step 2: Convert to fraction form
    85.23/128.01 = 81.39/x
  3. Step 3: Cross multiply
    85.23x = 128.01 × 81.39
  4. Step 4: Simplify right side
    85.23x = 10,418.73
  5. Step 5: Solve for x
    x = 10,418.73/85.23
  6. Step 6: Final answer
    x = 122.24

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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.