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Finding the Fourth Proportional to 31.01, 42.78 and 18.72

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Solution

The fourth proportional to 31.01, 42.78 and 18.72 is: 25.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.01 : 42.78 = 18.72 : x
  2. Step 2: Convert to fraction form
    31.01/42.78 = 18.72/x
  3. Step 3: Cross multiply
    31.01x = 42.78 × 18.72
  4. Step 4: Simplify right side
    31.01x = 800.84
  5. Step 5: Solve for x
    x = 800.84/31.01
  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.