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Finding the Fourth Proportional to 39.81, 54.21 and 39.72

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Solution

The fourth proportional to 39.81, 54.21 and 39.72 is: 54.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.81 : 54.21 = 39.72 : x
  2. Step 2: Convert to fraction form
    39.81/54.21 = 39.72/x
  3. Step 3: Cross multiply
    39.81x = 54.21 × 39.72
  4. Step 4: Simplify right side
    39.81x = 2,153.22
  5. Step 5: Solve for x
    x = 2,153.22/39.81
  6. Step 6: Final answer
    x = 54.09

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Why These Related Problems?

These problems maintain the same ratio (1.36) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.