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Finding the Fourth Proportional to 85.11, 128.26 and 80.99

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Solution

The fourth proportional to 85.11, 128.26 and 80.99 is: 122.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.11 : 128.26 = 80.99 : x
  2. Step 2: Convert to fraction form
    85.11/128.26 = 80.99/x
  3. Step 3: Cross multiply
    85.11x = 128.26 × 80.99
  4. Step 4: Simplify right side
    85.11x = 10,387.26
  5. Step 5: Solve for x
    x = 10,387.26/85.11
  6. Step 6: Final answer
    x = 122.05

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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.