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Finding the Fourth Proportional to 87.19, 120.36 and 85.39

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Solution

The fourth proportional to 87.19, 120.36 and 85.39 is: 117.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.19 : 120.36 = 85.39 : x
  2. Step 2: Convert to fraction form
    87.19/120.36 = 85.39/x
  3. Step 3: Cross multiply
    87.19x = 120.36 × 85.39
  4. Step 4: Simplify right side
    87.19x = 10,277.54
  5. Step 5: Solve for x
    x = 10,277.54/87.19
  6. Step 6: Final answer
    x = 117.88

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.