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Finding the Fourth Proportional to 39.97, 55.02 and 31.78

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Solution

The fourth proportional to 39.97, 55.02 and 31.78 is: 43.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.97 : 55.02 = 31.78 : x
  2. Step 2: Convert to fraction form
    39.97/55.02 = 31.78/x
  3. Step 3: Cross multiply
    39.97x = 55.02 × 31.78
  4. Step 4: Simplify right side
    39.97x = 1,748.54
  5. Step 5: Solve for x
    x = 1,748.54/39.97
  6. Step 6: Final answer
    x = 43.75

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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.