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Finding the Fourth Proportional to 20.81, 31.22 and 6.56

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Solution

The fourth proportional to 20.81, 31.22 and 6.56 is: 9.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.81 : 31.22 = 6.56 : x
  2. Step 2: Convert to fraction form
    20.81/31.22 = 6.56/x
  3. Step 3: Cross multiply
    20.81x = 31.22 × 6.56
  4. Step 4: Simplify right side
    20.81x = 204.80
  5. Step 5: Solve for x
    x = 204.80/20.81
  6. Step 6: Final answer
    x = 9.84

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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.