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Finding the Fourth Proportional to 31.85, 47.78 and 13.57

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Solution

The fourth proportional to 31.85, 47.78 and 13.57 is: 20.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.85 : 47.78 = 13.57 : x
  2. Step 2: Convert to fraction form
    31.85/47.78 = 13.57/x
  3. Step 3: Cross multiply
    31.85x = 47.78 × 13.57
  4. Step 4: Simplify right side
    31.85x = 648.37
  5. Step 5: Solve for x
    x = 648.37/31.85
  6. Step 6: Final answer
    x = 20.36

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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.