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Finding the Fourth Proportional to 20.60, 30.91 and 9.91

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Solution

The fourth proportional to 20.60, 30.91 and 9.91 is: 14.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.60 : 30.91 = 9.91 : x
  2. Step 2: Convert to fraction form
    20.60/30.91 = 9.91/x
  3. Step 3: Cross multiply
    20.60x = 30.91 × 9.91
  4. Step 4: Simplify right side
    20.60x = 306.22
  5. Step 5: Solve for x
    x = 306.22/20.60
  6. Step 6: Final answer
    x = 14.87

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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.