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Finding the Fourth Proportional to 13.17, 19.80 and 12.90

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Solution

The fourth proportional to 13.17, 19.80 and 12.90 is: 19.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.17 : 19.80 = 12.90 : x
  2. Step 2: Convert to fraction form
    13.17/19.80 = 12.90/x
  3. Step 3: Cross multiply
    13.17x = 19.80 × 12.90
  4. Step 4: Simplify right side
    13.17x = 255.42
  5. Step 5: Solve for x
    x = 255.42/13.17
  6. Step 6: Final answer
    x = 19.39

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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.