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Finding the Fourth Proportional to 13.72, 20.55 and 13.21

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Solution

The fourth proportional to 13.72, 20.55 and 13.21 is: 19.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.72 : 20.55 = 13.21 : x
  2. Step 2: Convert to fraction form
    13.72/20.55 = 13.21/x
  3. Step 3: Cross multiply
    13.72x = 20.55 × 13.21
  4. Step 4: Simplify right side
    13.72x = 271.47
  5. Step 5: Solve for x
    x = 271.47/13.72
  6. Step 6: Final answer
    x = 19.79

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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.