Finding the Fourth Proportional to 20,792.42, 31,196.37 and 12,478.40

Step by Step Solution

1. Step 1: Write the proportion equation
   20,792.42 : 31,196.37 = 12,478.40 : x
2. Step 2: Convert to fraction form
   20,792.42/31,196.37 = 12,478.40/x
3. Step 3: Cross multiply
   20,792.42x = 31,196.37 × 12,478.40
4. Step 4: Simplify right side
   20,792.42x = 389,280,783.41
5. Step 5: Solve for x
   x = 389,280,783.41/20,792.42
6. Step 6: Final answer
   x = 18,722.25