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Finding the Fourth Proportional to 20.15, 27.81 and 12.86

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Solution

The fourth proportional to 20.15, 27.81 and 12.86 is: 17.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.15 : 27.81 = 12.86 : x
  2. Step 2: Convert to fraction form
    20.15/27.81 = 12.86/x
  3. Step 3: Cross multiply
    20.15x = 27.81 × 12.86
  4. Step 4: Simplify right side
    20.15x = 357.60
  5. Step 5: Solve for x
    x = 357.60/20.15
  6. Step 6: Final answer
    x = 17.75

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.