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Finding the Fourth Proportional to 20.89, 31.15 and 18.97

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Solution

The fourth proportional to 20.89, 31.15 and 18.97 is: 28.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.89 : 31.15 = 18.97 : x
  2. Step 2: Convert to fraction form
    20.89/31.15 = 18.97/x
  3. Step 3: Cross multiply
    20.89x = 31.15 × 18.97
  4. Step 4: Simplify right side
    20.89x = 590.86
  5. Step 5: Solve for x
    x = 590.86/20.89
  6. Step 6: Final answer
    x = 28.28

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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.