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Finding the Fourth Proportional to 13.72, 20.45 and 13.28

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Solution

The fourth proportional to 13.72, 20.45 and 13.28 is: 19.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.72 : 20.45 = 13.28 : x
  2. Step 2: Convert to fraction form
    13.72/20.45 = 13.28/x
  3. Step 3: Cross multiply
    13.72x = 20.45 × 13.28
  4. Step 4: Simplify right side
    13.72x = 271.58
  5. Step 5: Solve for x
    x = 271.58/13.72
  6. Step 6: Final answer
    x = 19.79

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.