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Finding the Fourth Proportional to 13.85, 20.87 and 13.80

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Solution

The fourth proportional to 13.85, 20.87 and 13.80 is: 20.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.85 : 20.87 = 13.80 : x
  2. Step 2: Convert to fraction form
    13.85/20.87 = 13.80/x
  3. Step 3: Cross multiply
    13.85x = 20.87 × 13.80
  4. Step 4: Simplify right side
    13.85x = 288.01
  5. Step 5: Solve for x
    x = 288.01/13.85
  6. Step 6: Final answer
    x = 20.79

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.