Finding the Fourth Proportional to 22,991.60, 31,728.32 and 12,920.32

Step by Step Solution

1. Step 1: Write the proportion equation
   22,991.60 : 31,728.32 = 12,920.32 : x
2. Step 2: Convert to fraction form
   22,991.60/31,728.32 = 12,920.32/x
3. Step 3: Cross multiply
   22,991.60x = 31,728.32 × 12,920.32
4. Step 4: Simplify right side
   22,991.60x = 409,940,047.46
5. Step 5: Solve for x
   x = 409,940,047.46/22,991.60
6. Step 6: Final answer
   x = 17,829.99