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Finding the Fourth Proportional to 86.86, 120.39 and 85.58

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Solution

The fourth proportional to 86.86, 120.39 and 85.58 is: 118.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.86 : 120.39 = 85.58 : x
  2. Step 2: Convert to fraction form
    86.86/120.39 = 85.58/x
  3. Step 3: Cross multiply
    86.86x = 120.39 × 85.58
  4. Step 4: Simplify right side
    86.86x = 10,302.98
  5. Step 5: Solve for x
    x = 10,302.98/86.86
  6. Step 6: Final answer
    x = 118.62

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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.