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Finding the Fourth Proportional to 18.90, 28.21 and 13.43

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Solution

The fourth proportional to 18.90, 28.21 and 13.43 is: 20.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    18.90 : 28.21 = 13.43 : x
  2. Step 2: Convert to fraction form
    18.90/28.21 = 13.43/x
  3. Step 3: Cross multiply
    18.90x = 28.21 × 13.43
  4. Step 4: Simplify right side
    18.90x = 378.86
  5. Step 5: Solve for x
    x = 378.86/18.90
  6. Step 6: Final answer
    x = 20.05

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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.