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Finding the Fourth Proportional to 20.43, 30.74 and 19.21

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Solution

The fourth proportional to 20.43, 30.74 and 19.21 is: 28.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.43 : 30.74 = 19.21 : x
  2. Step 2: Convert to fraction form
    20.43/30.74 = 19.21/x
  3. Step 3: Cross multiply
    20.43x = 30.74 × 19.21
  4. Step 4: Simplify right side
    20.43x = 590.42
  5. Step 5: Solve for x
    x = 590.42/20.43
  6. Step 6: Final answer
    x = 28.91

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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.