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Finding the Fourth Proportional to 84.92, 128.13 and 81.75

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Solution

The fourth proportional to 84.92, 128.13 and 81.75 is: 123.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.92 : 128.13 = 81.75 : x
  2. Step 2: Convert to fraction form
    84.92/128.13 = 81.75/x
  3. Step 3: Cross multiply
    84.92x = 128.13 × 81.75
  4. Step 4: Simplify right side
    84.92x = 10,474.80
  5. Step 5: Solve for x
    x = 10,474.80/84.92
  6. Step 6: Final answer
    x = 123.36

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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.