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Finding the Fourth Proportional to 31.00, 42.78 and 18.71

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Solution

The fourth proportional to 31.00, 42.78 and 18.71 is: 25.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.00 : 42.78 = 18.71 : x
  2. Step 2: Convert to fraction form
    31.00/42.78 = 18.71/x
  3. Step 3: Cross multiply
    31.00x = 42.78 × 18.71
  4. Step 4: Simplify right side
    31.00x = 800.57
  5. Step 5: Solve for x
    x = 800.57/31.00
  6. Step 6: Final answer
    x = 25.83

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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.