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Finding the Fourth Proportional to 13.78, 18.99 and 13.31

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Solution

The fourth proportional to 13.78, 18.99 and 13.31 is: 18.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.78 : 18.99 = 13.31 : x
  2. Step 2: Convert to fraction form
    13.78/18.99 = 13.31/x
  3. Step 3: Cross multiply
    13.78x = 18.99 × 13.31
  4. Step 4: Simplify right side
    13.78x = 252.76
  5. Step 5: Solve for x
    x = 252.76/13.78
  6. Step 6: Final answer
    x = 18.34

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.