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Finding the Fourth Proportional to 31.91, 47.86 and 13.87

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Solution

The fourth proportional to 31.91, 47.86 and 13.87 is: 20.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.91 : 47.86 = 13.87 : x
  2. Step 2: Convert to fraction form
    31.91/47.86 = 13.87/x
  3. Step 3: Cross multiply
    31.91x = 47.86 × 13.87
  4. Step 4: Simplify right side
    31.91x = 663.66
  5. Step 5: Solve for x
    x = 663.66/31.91
  6. Step 6: Final answer
    x = 20.80

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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.