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Finding the Fourth Proportional to 31.91, 47.84 and 21.79

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Solution

The fourth proportional to 31.91, 47.84 and 21.79 is: 32.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.91 : 47.84 = 21.79 : x
  2. Step 2: Convert to fraction form
    31.91/47.84 = 21.79/x
  3. Step 3: Cross multiply
    31.91x = 47.84 × 21.79
  4. Step 4: Simplify right side
    31.91x = 1,042.19
  5. Step 5: Solve for x
    x = 1,042.19/31.91
  6. Step 6: Final answer
    x = 32.66

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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.