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Finding the Fourth Proportional to 31.22, 42.82 and 30.86

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Solution

The fourth proportional to 31.22, 42.82 and 30.86 is: 42.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.22 : 42.82 = 30.86 : x
  2. Step 2: Convert to fraction form
    31.22/42.82 = 30.86/x
  3. Step 3: Cross multiply
    31.22x = 42.82 × 30.86
  4. Step 4: Simplify right side
    31.22x = 1,321.43
  5. Step 5: Solve for x
    x = 1,321.43/31.22
  6. Step 6: Final answer
    x = 42.33

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.