Finding the Fourth Proportional to 22,406.78, 30,921.78 and 12,980.80

Step by Step Solution

1. Step 1: Write the proportion equation
   22,406.78 : 30,921.78 = 12,980.80 : x
2. Step 2: Convert to fraction form
   22,406.78/30,921.78 = 12,980.80/x
3. Step 3: Cross multiply
   22,406.78x = 30,921.78 × 12,980.80
4. Step 4: Simplify right side
   22,406.78x = 401,389,441.82
5. Step 5: Solve for x
   x = 401,389,441.82/22,406.78
6. Step 6: Final answer
   x = 17,913.75