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Finding the Fourth Proportional to 20.81, 31.23 and 18.12

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Solution

The fourth proportional to 20.81, 31.23 and 18.12 is: 27.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.81 : 31.23 = 18.12 : x
  2. Step 2: Convert to fraction form
    20.81/31.23 = 18.12/x
  3. Step 3: Cross multiply
    20.81x = 31.23 × 18.12
  4. Step 4: Simplify right side
    20.81x = 565.89
  5. Step 5: Solve for x
    x = 565.89/20.81
  6. Step 6: Final answer
    x = 27.20

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.