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Finding the Fourth Proportional to 85.97, 128.31 and 83.92

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Solution

The fourth proportional to 85.97, 128.31 and 83.92 is: 125.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.97 : 128.31 = 83.92 : x
  2. Step 2: Convert to fraction form
    85.97/128.31 = 83.92/x
  3. Step 3: Cross multiply
    85.97x = 128.31 × 83.92
  4. Step 4: Simplify right side
    85.97x = 10,767.78
  5. Step 5: Solve for x
    x = 10,767.78/85.97
  6. Step 6: Final answer
    x = 125.25

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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.