Finding the Fourth Proportional to 8,721.45, 13,074.20 and 3,789.31

Step by Step Solution

1. Step 1: Write the proportion equation
   8,721.45 : 13,074.20 = 3,789.31 : x
2. Step 2: Convert to fraction form
   8,721.45/13,074.20 = 3,789.31/x
3. Step 3: Cross multiply
   8,721.45x = 13,074.20 × 3,789.31
4. Step 4: Simplify right side
   8,721.45x = 49,542,196.80
5. Step 5: Solve for x
   x = 49,542,196.80/8,721.45
6. Step 6: Final answer
   x = 5,680.50