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Finding the Fourth Proportional to 31.85, 47.72 and 21.54

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Solution

The fourth proportional to 31.85, 47.72 and 21.54 is: 32.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.85 : 47.72 = 21.54 : x
  2. Step 2: Convert to fraction form
    31.85/47.72 = 21.54/x
  3. Step 3: Cross multiply
    31.85x = 47.72 × 21.54
  4. Step 4: Simplify right side
    31.85x = 1,027.89
  5. Step 5: Solve for x
    x = 1,027.89/31.85
  6. Step 6: Final answer
    x = 32.28

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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.