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Finding the Fourth Proportional to 39.72, 54.49 and 38.90

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Solution

The fourth proportional to 39.72, 54.49 and 38.90 is: 53.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.72 : 54.49 = 38.90 : x
  2. Step 2: Convert to fraction form
    39.72/54.49 = 38.90/x
  3. Step 3: Cross multiply
    39.72x = 54.49 × 38.90
  4. Step 4: Simplify right side
    39.72x = 2,119.66
  5. Step 5: Solve for x
    x = 2,119.66/39.72
  6. Step 6: Final answer
    x = 53.37

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.