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Finding the Fourth Proportional to 39.89, 59.80 and 20.64

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Solution

The fourth proportional to 39.89, 59.80 and 20.64 is: 30.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.89 : 59.80 = 20.64 : x
  2. Step 2: Convert to fraction form
    39.89/59.80 = 20.64/x
  3. Step 3: Cross multiply
    39.89x = 59.80 × 20.64
  4. Step 4: Simplify right side
    39.89x = 1,234.27
  5. Step 5: Solve for x
    x = 1,234.27/39.89
  6. Step 6: Final answer
    x = 30.94

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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.