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Finding the Fourth Proportional to 86.62, 129.80 and 80.85

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Solution

The fourth proportional to 86.62, 129.80 and 80.85 is: 121.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.62 : 129.80 = 80.85 : x
  2. Step 2: Convert to fraction form
    86.62/129.80 = 80.85/x
  3. Step 3: Cross multiply
    86.62x = 129.80 × 80.85
  4. Step 4: Simplify right side
    86.62x = 10,494.33
  5. Step 5: Solve for x
    x = 10,494.33/86.62
  6. Step 6: Final answer
    x = 121.15

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.