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Finding the Fourth Proportional to 20.65, 28.49 and 11.90

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Solution

The fourth proportional to 20.65, 28.49 and 11.90 is: 16.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.65 : 28.49 = 11.90 : x
  2. Step 2: Convert to fraction form
    20.65/28.49 = 11.90/x
  3. Step 3: Cross multiply
    20.65x = 28.49 × 11.90
  4. Step 4: Simplify right side
    20.65x = 339.03
  5. Step 5: Solve for x
    x = 339.03/20.65
  6. Step 6: Final answer
    x = 16.42

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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.