Finding the Fourth Proportional to 21,131.92, 31,693.42 and 13,612.96

Step by Step Solution

1. Step 1: Write the proportion equation
   21,131.92 : 31,693.42 = 13,612.96 : x
2. Step 2: Convert to fraction form
   21,131.92/31,693.42 = 13,612.96/x
3. Step 3: Cross multiply
   21,131.92x = 31,693.42 × 13,612.96
4. Step 4: Simplify right side
   21,131.92x = 431,441,258.72
5. Step 5: Solve for x
   x = 431,441,258.72/21,131.92
6. Step 6: Final answer
   x = 20,416.57