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Finding the Fourth Proportional to 21.88, 30.22 and 20.90

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Solution

The fourth proportional to 21.88, 30.22 and 20.90 is: 28.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.88 : 30.22 = 20.90 : x
  2. Step 2: Convert to fraction form
    21.88/30.22 = 20.90/x
  3. Step 3: Cross multiply
    21.88x = 30.22 × 20.90
  4. Step 4: Simplify right side
    21.88x = 631.60
  5. Step 5: Solve for x
    x = 631.60/21.88
  6. Step 6: Final answer
    x = 28.87

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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.