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Finding the Fourth Proportional to 13.50, 20.21 and 12.78

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Solution

The fourth proportional to 13.50, 20.21 and 12.78 is: 19.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.50 : 20.21 = 12.78 : x
  2. Step 2: Convert to fraction form
    13.50/20.21 = 12.78/x
  3. Step 3: Cross multiply
    13.50x = 20.21 × 12.78
  4. Step 4: Simplify right side
    13.50x = 258.22
  5. Step 5: Solve for x
    x = 258.22/13.50
  6. Step 6: Final answer
    x = 19.13

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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.