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Finding the Fourth Proportional to 18.69, 28.05 and 11.91

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Solution

The fourth proportional to 18.69, 28.05 and 11.91 is: 17.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    18.69 : 28.05 = 11.91 : x
  2. Step 2: Convert to fraction form
    18.69/28.05 = 11.91/x
  3. Step 3: Cross multiply
    18.69x = 28.05 × 11.91
  4. Step 4: Simplify right side
    18.69x = 334.08
  5. Step 5: Solve for x
    x = 334.08/18.69
  6. Step 6: Final answer
    x = 17.87

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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.