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Finding the Fourth Proportional to 20.88, 31.31 and 6.43

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Solution

The fourth proportional to 20.88, 31.31 and 6.43 is: 9.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.88 : 31.31 = 6.43 : x
  2. Step 2: Convert to fraction form
    20.88/31.31 = 6.43/x
  3. Step 3: Cross multiply
    20.88x = 31.31 × 6.43
  4. Step 4: Simplify right side
    20.88x = 201.31
  5. Step 5: Solve for x
    x = 201.31/20.88
  6. Step 6: Final answer
    x = 9.64

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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.