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Finding the Fourth Proportional to 31.86, 47.78 and 13.84

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Solution

The fourth proportional to 31.86, 47.78 and 13.84 is: 20.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.86 : 47.78 = 13.84 : x
  2. Step 2: Convert to fraction form
    31.86/47.78 = 13.84/x
  3. Step 3: Cross multiply
    31.86x = 47.78 × 13.84
  4. Step 4: Simplify right side
    31.86x = 661.21
  5. Step 5: Solve for x
    x = 661.21/31.86
  6. Step 6: Final answer
    x = 20.76

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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.