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Finding the Fourth Proportional to 13.20, 19.70 and 12.78

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Solution

The fourth proportional to 13.20, 19.70 and 12.78 is: 19.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.20 : 19.70 = 12.78 : x
  2. Step 2: Convert to fraction form
    13.20/19.70 = 12.78/x
  3. Step 3: Cross multiply
    13.20x = 19.70 × 12.78
  4. Step 4: Simplify right side
    13.20x = 251.77
  5. Step 5: Solve for x
    x = 251.77/13.20
  6. Step 6: Final answer
    x = 19.07

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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.