Finding the Fourth Proportional to 408,738.42, 613,211.34 and 128,258.10

Step by Step Solution

1. Step 1: Write the proportion equation
   408,738.42 : 613,211.34 = 128,258.10 : x
2. Step 2: Convert to fraction form
   408,738.42/613,211.34 = 128,258.10/x
3. Step 3: Cross multiply
   408,738.42x = 613,211.34 × 128,258.10
4. Step 4: Simplify right side
   408,738.42x = 78,649,321,366.85
5. Step 5: Solve for x
   x = 78,649,321,366.85/408,738.42
6. Step 6: Final answer
   x = 192,419.69