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Finding the Fourth Proportional to 39.40, 54.31 and 34.72

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Solution

The fourth proportional to 39.40, 54.31 and 34.72 is: 47.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.40 : 54.31 = 34.72 : x
  2. Step 2: Convert to fraction form
    39.40/54.31 = 34.72/x
  3. Step 3: Cross multiply
    39.40x = 54.31 × 34.72
  4. Step 4: Simplify right side
    39.40x = 1,885.64
  5. Step 5: Solve for x
    x = 1,885.64/39.40
  6. Step 6: Final answer
    x = 47.86

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.