Finding the Fourth Proportional to 419,399.76, 578,788.05 and 238,128.57

Step by Step Solution

1. Step 1: Write the proportion equation
   419,399.76 : 578,788.05 = 238,128.57 : x
2. Step 2: Convert to fraction form
   419,399.76/578,788.05 = 238,128.57/x
3. Step 3: Cross multiply
   419,399.76x = 578,788.05 × 238,128.57
4. Step 4: Simplify right side
   419,399.76x = 137,825,970,679.59
5. Step 5: Solve for x
   x = 137,825,970,679.59/419,399.76
6. Step 6: Final answer
   x = 328,626.73