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Finding the Fourth Proportional to 28.11, 38.80 and 21.22

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Solution

The fourth proportional to 28.11, 38.80 and 21.22 is: 29.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.11 : 38.80 = 21.22 : x
  2. Step 2: Convert to fraction form
    28.11/38.80 = 21.22/x
  3. Step 3: Cross multiply
    28.11x = 38.80 × 21.22
  4. Step 4: Simplify right side
    28.11x = 823.28
  5. Step 5: Solve for x
    x = 823.28/28.11
  6. Step 6: Final answer
    x = 29.29

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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.