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Finding the Fourth Proportional to 28.18, 42.21 and 20.98

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Solution

The fourth proportional to 28.18, 42.21 and 20.98 is: 31.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.18 : 42.21 = 20.98 : x
  2. Step 2: Convert to fraction form
    28.18/42.21 = 20.98/x
  3. Step 3: Cross multiply
    28.18x = 42.21 × 20.98
  4. Step 4: Simplify right side
    28.18x = 885.57
  5. Step 5: Solve for x
    x = 885.57/28.18
  6. Step 6: Final answer
    x = 31.43

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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.