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Finding the Fourth Proportional to 19.91, 29.85 and 13.90

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Solution

The fourth proportional to 19.91, 29.85 and 13.90 is: 20.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    19.91 : 29.85 = 13.90 : x
  2. Step 2: Convert to fraction form
    19.91/29.85 = 13.90/x
  3. Step 3: Cross multiply
    19.91x = 29.85 × 13.90
  4. Step 4: Simplify right side
    19.91x = 414.77
  5. Step 5: Solve for x
    x = 414.77/19.91
  6. Step 6: Final answer
    x = 20.84

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.