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Finding the Fourth Proportional to 42.21, 63.32 and 20.55

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Solution

The fourth proportional to 42.21, 63.32 and 20.55 is: 30.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.21 : 63.32 = 20.55 : x
  2. Step 2: Convert to fraction form
    42.21/63.32 = 20.55/x
  3. Step 3: Cross multiply
    42.21x = 63.32 × 20.55
  4. Step 4: Simplify right side
    42.21x = 1,301.12
  5. Step 5: Solve for x
    x = 1,301.12/42.21
  6. Step 6: Final answer
    x = 30.83

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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.