Finding the Fourth Proportional to 128,998.56, 178,021.20 and 72,414.24

Step by Step Solution

1. Step 1: Write the proportion equation
   128,998.56 : 178,021.20 = 72,414.24 : x
2. Step 2: Convert to fraction form
   128,998.56/178,021.20 = 72,414.24/x
3. Step 3: Cross multiply
   128,998.56x = 178,021.20 × 72,414.24
4. Step 4: Simplify right side
   128,998.56x = 12,891,269,901.89
5. Step 5: Solve for x
   x = 12,891,269,901.89/128,998.56
6. Step 6: Final answer
   x = 99,933.44