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Finding the Fourth Proportional to 20.98, 28.80 and 19.90

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Solution

The fourth proportional to 20.98, 28.80 and 19.90 is: 27.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.98 : 28.80 = 19.90 : x
  2. Step 2: Convert to fraction form
    20.98/28.80 = 19.90/x
  3. Step 3: Cross multiply
    20.98x = 28.80 × 19.90
  4. Step 4: Simplify right side
    20.98x = 573.12
  5. Step 5: Solve for x
    x = 573.12/20.98
  6. Step 6: Final answer
    x = 27.32

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.