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Finding the Fourth Proportional to 31.86, 43.94 and 20.81

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Solution

The fourth proportional to 31.86, 43.94 and 20.81 is: 28.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.86 : 43.94 = 20.81 : x
  2. Step 2: Convert to fraction form
    31.86/43.94 = 20.81/x
  3. Step 3: Cross multiply
    31.86x = 43.94 × 20.81
  4. Step 4: Simplify right side
    31.86x = 914.55
  5. Step 5: Solve for x
    x = 914.55/31.86
  6. Step 6: Final answer
    x = 28.71

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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.