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Finding the Fourth Proportional to 20.98, 31.32 and 19.28

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Solution

The fourth proportional to 20.98, 31.32 and 19.28 is: 28.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.98 : 31.32 = 19.28 : x
  2. Step 2: Convert to fraction form
    20.98/31.32 = 19.28/x
  3. Step 3: Cross multiply
    20.98x = 31.32 × 19.28
  4. Step 4: Simplify right side
    20.98x = 603.85
  5. Step 5: Solve for x
    x = 603.85/20.98
  6. Step 6: Final answer
    x = 28.78

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.