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Finding the Fourth Proportional to 31.12, 43.24 and 30.81

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Solution

The fourth proportional to 31.12, 43.24 and 30.81 is: 42.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.12 : 43.24 = 30.81 : x
  2. Step 2: Convert to fraction form
    31.12/43.24 = 30.81/x
  3. Step 3: Cross multiply
    31.12x = 43.24 × 30.81
  4. Step 4: Simplify right side
    31.12x = 1,332.22
  5. Step 5: Solve for x
    x = 1,332.22/31.12
  6. Step 6: Final answer
    x = 42.81

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.