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Finding the Fourth Proportional to 87.78, 120.42 and 85.68

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Solution

The fourth proportional to 87.78, 120.42 and 85.68 is: 117.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.78 : 120.42 = 85.68 : x
  2. Step 2: Convert to fraction form
    87.78/120.42 = 85.68/x
  3. Step 3: Cross multiply
    87.78x = 120.42 × 85.68
  4. Step 4: Simplify right side
    87.78x = 10,317.59
  5. Step 5: Solve for x
    x = 10,317.59/87.78
  6. Step 6: Final answer
    x = 117.54

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.