Finding the Fourth Proportional to 21,005, 31,529.82 and 12,705.96

Step by Step Solution

1. Step 1: Write the proportion equation
   21,005 : 31,529.82 = 12,705.96 : x
2. Step 2: Convert to fraction form
   21,005/31,529.82 = 12,705.96/x
3. Step 3: Cross multiply
   21,005x = 31,529.82 × 12,705.96
4. Step 4: Simplify right side
   21,005x = 400,616,631.73
5. Step 5: Solve for x
   x = 400,616,631.73/21,005
6. Step 6: Final answer
   x = 19,072.44