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Finding the Fourth Proportional to 18.71, 25.81 and 12.89

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Solution

The fourth proportional to 18.71, 25.81 and 12.89 is: 17.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    18.71 : 25.81 = 12.89 : x
  2. Step 2: Convert to fraction form
    18.71/25.81 = 12.89/x
  3. Step 3: Cross multiply
    18.71x = 25.81 × 12.89
  4. Step 4: Simplify right side
    18.71x = 332.55
  5. Step 5: Solve for x
    x = 332.55/18.71
  6. Step 6: Final answer
    x = 17.78

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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.