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Finding the Fourth Proportional to 21.75, 29.97 and 20.47

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Solution

The fourth proportional to 21.75, 29.97 and 20.47 is: 28.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.75 : 29.97 = 20.47 : x
  2. Step 2: Convert to fraction form
    21.75/29.97 = 20.47/x
  3. Step 3: Cross multiply
    21.75x = 29.97 × 20.47
  4. Step 4: Simplify right side
    21.75x = 613.49
  5. Step 5: Solve for x
    x = 613.49/21.75
  6. Step 6: Final answer
    x = 28.21

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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.