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Finding the Fourth Proportional to 13.31, 19.80 and 12.87

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Solution

The fourth proportional to 13.31, 19.80 and 12.87 is: 19.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.31 : 19.80 = 12.87 : x
  2. Step 2: Convert to fraction form
    13.31/19.80 = 12.87/x
  3. Step 3: Cross multiply
    13.31x = 19.80 × 12.87
  4. Step 4: Simplify right side
    13.31x = 254.83
  5. Step 5: Solve for x
    x = 254.83/13.31
  6. Step 6: Final answer
    x = 19.15

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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.