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Finding the Fourth Proportional to 85.08, 126.87 and 81.57

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Solution

The fourth proportional to 85.08, 126.87 and 81.57 is: 121.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.08 : 126.87 = 81.57 : x
  2. Step 2: Convert to fraction form
    85.08/126.87 = 81.57/x
  3. Step 3: Cross multiply
    85.08x = 126.87 × 81.57
  4. Step 4: Simplify right side
    85.08x = 10,348.79
  5. Step 5: Solve for x
    x = 10,348.79/85.08
  6. Step 6: Final answer
    x = 121.64

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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.