Finding the Fourth Proportional to 21,928.83, 30,266.78 and 12,981.57

Step by Step Solution

1. Step 1: Write the proportion equation
   21,928.83 : 30,266.78 = 12,981.57 : x
2. Step 2: Convert to fraction form
   21,928.83/30,266.78 = 12,981.57/x
3. Step 3: Cross multiply
   21,928.83x = 30,266.78 × 12,981.57
4. Step 4: Simplify right side
   21,928.83x = 392,910,258.34
5. Step 5: Solve for x
   x = 392,910,258.34/21,928.83
6. Step 6: Final answer
   x = 17,917.52