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Finding the Fourth Proportional to 20.15, 30.21 and 9.86

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Solution

The fourth proportional to 20.15, 30.21 and 9.86 is: 14.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.15 : 30.21 = 9.86 : x
  2. Step 2: Convert to fraction form
    20.15/30.21 = 9.86/x
  3. Step 3: Cross multiply
    20.15x = 30.21 × 9.86
  4. Step 4: Simplify right side
    20.15x = 297.93
  5. Step 5: Solve for x
    x = 297.93/20.15
  6. Step 6: Final answer
    x = 14.78

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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.