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Finding the Fourth Proportional to 31.88, 47.80 and 19.86

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Solution

The fourth proportional to 31.88, 47.80 and 19.86 is: 29.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.88 : 47.80 = 19.86 : x
  2. Step 2: Convert to fraction form
    31.88/47.80 = 19.86/x
  3. Step 3: Cross multiply
    31.88x = 47.80 × 19.86
  4. Step 4: Simplify right side
    31.88x = 949.31
  5. Step 5: Solve for x
    x = 949.31/31.88
  6. Step 6: Final answer
    x = 29.78

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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.