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Finding the Fourth Proportional to 87.17, 120.80 and 85.55

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Solution

The fourth proportional to 87.17, 120.80 and 85.55 is: 118.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.17 : 120.80 = 85.55 : x
  2. Step 2: Convert to fraction form
    87.17/120.80 = 85.55/x
  3. Step 3: Cross multiply
    87.17x = 120.80 × 85.55
  4. Step 4: Simplify right side
    87.17x = 10,334.05
  5. Step 5: Solve for x
    x = 10,334.05/87.17
  6. Step 6: Final answer
    x = 118.56

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.