Finding the Fourth Proportional to 21,078.96, 31,608.72 and 12,316.56

Step by Step Solution

1. Step 1: Write the proportion equation
   21,078.96 : 31,608.72 = 12,316.56 : x
2. Step 2: Convert to fraction form
   21,078.96/31,608.72 = 12,316.56/x
3. Step 3: Cross multiply
   21,078.96x = 31,608.72 × 12,316.56
4. Step 4: Simplify right side
   21,078.96x = 389,310,696.40
5. Step 5: Solve for x
   x = 389,310,696.40/21,078.96
6. Step 6: Final answer
   x = 18,469.16