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Finding the Fourth Proportional to 31.91, 47.85 and 20.51

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Solution

The fourth proportional to 31.91, 47.85 and 20.51 is: 30.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.91 : 47.85 = 20.51 : x
  2. Step 2: Convert to fraction form
    31.91/47.85 = 20.51/x
  3. Step 3: Cross multiply
    31.91x = 47.85 × 20.51
  4. Step 4: Simplify right side
    31.91x = 981.40
  5. Step 5: Solve for x
    x = 981.40/31.91
  6. Step 6: Final answer
    x = 30.76

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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.