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Finding the Fourth Proportional to 31.77, 43.86 and 20.85

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Solution

The fourth proportional to 31.77, 43.86 and 20.85 is: 28.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.77 : 43.86 = 20.85 : x
  2. Step 2: Convert to fraction form
    31.77/43.86 = 20.85/x
  3. Step 3: Cross multiply
    31.77x = 43.86 × 20.85
  4. Step 4: Simplify right side
    31.77x = 914.48
  5. Step 5: Solve for x
    x = 914.48/31.77
  6. Step 6: Final answer
    x = 28.78

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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.