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Finding the Fourth Proportional to 20.91, 31.16 and 19.83

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Solution

The fourth proportional to 20.91, 31.16 and 19.83 is: 29.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.91 : 31.16 = 19.83 : x
  2. Step 2: Convert to fraction form
    20.91/31.16 = 19.83/x
  3. Step 3: Cross multiply
    20.91x = 31.16 × 19.83
  4. Step 4: Simplify right side
    20.91x = 617.80
  5. Step 5: Solve for x
    x = 617.80/20.91
  6. Step 6: Final answer
    x = 29.55

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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.