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Finding the Fourth Proportional to 85.74, 128.67 and 80.61

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Solution

The fourth proportional to 85.74, 128.67 and 80.61 is: 120.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.74 : 128.67 = 80.61 : x
  2. Step 2: Convert to fraction form
    85.74/128.67 = 80.61/x
  3. Step 3: Cross multiply
    85.74x = 128.67 × 80.61
  4. Step 4: Simplify right side
    85.74x = 10,372.09
  5. Step 5: Solve for x
    x = 10,372.09/85.74
  6. Step 6: Final answer
    x = 120.97

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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.