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Finding the Fourth Proportional to 31.39, 47.02 and 20.55

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Solution

The fourth proportional to 31.39, 47.02 and 20.55 is: 30.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.39 : 47.02 = 20.55 : x
  2. Step 2: Convert to fraction form
    31.39/47.02 = 20.55/x
  3. Step 3: Cross multiply
    31.39x = 47.02 × 20.55
  4. Step 4: Simplify right side
    31.39x = 966.26
  5. Step 5: Solve for x
    x = 966.26/31.39
  6. Step 6: Final answer
    x = 30.78

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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.