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Finding the Fourth Proportional to 31.87, 47.85 and 19.81

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Solution

The fourth proportional to 31.87, 47.85 and 19.81 is: 29.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.87 : 47.85 = 19.81 : x
  2. Step 2: Convert to fraction form
    31.87/47.85 = 19.81/x
  3. Step 3: Cross multiply
    31.87x = 47.85 × 19.81
  4. Step 4: Simplify right side
    31.87x = 947.91
  5. Step 5: Solve for x
    x = 947.91/31.87
  6. Step 6: Final answer
    x = 29.74

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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.