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Finding the Fourth Proportional to 85.94, 129.18 and 81.08

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Solution

The fourth proportional to 85.94, 129.18 and 81.08 is: 121.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.94 : 129.18 = 81.08 : x
  2. Step 2: Convert to fraction form
    85.94/129.18 = 81.08/x
  3. Step 3: Cross multiply
    85.94x = 129.18 × 81.08
  4. Step 4: Simplify right side
    85.94x = 10,473.91
  5. Step 5: Solve for x
    x = 10,473.91/85.94
  6. Step 6: Final answer
    x = 121.87

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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.