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Finding the Fourth Proportional to 13.85, 20.75 and 8.15

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Solution

The fourth proportional to 13.85, 20.75 and 8.15 is: 12.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.85 : 20.75 = 8.15 : x
  2. Step 2: Convert to fraction form
    13.85/20.75 = 8.15/x
  3. Step 3: Cross multiply
    13.85x = 20.75 × 8.15
  4. Step 4: Simplify right side
    13.85x = 168.97
  5. Step 5: Solve for x
    x = 168.97/13.85
  6. Step 6: Final answer
    x = 12.20

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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.