Finding the Fourth Proportional to 13,380.61, 19,989.53 and 8,662.18

Step by Step Solution

1. Step 1: Write the proportion equation
   13,380.61 : 19,989.53 = 8,662.18 : x
2. Step 2: Convert to fraction form
   13,380.61/19,989.53 = 8,662.18/x
3. Step 3: Cross multiply
   13,380.61x = 19,989.53 × 8,662.18
4. Step 4: Simplify right side
   13,380.61x = 173,152,906.98
5. Step 5: Solve for x
   x = 173,152,906.98/13,380.61
6. Step 6: Final answer
   x = 12,940.58