Finding the Fourth Proportional to 1,399.38, 1,931.15 and 778.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.38 : 1,931.15 = 778.38 : x
2. Step 2: Convert to fraction form
   1,399.38/1,931.15 = 778.38/x
3. Step 3: Cross multiply
   1,399.38x = 1,931.15 × 778.38
4. Step 4: Simplify right side
   1,399.38x = 1,503,168.54
5. Step 5: Solve for x
   x = 1,503,168.54/1,399.38
6. Step 6: Final answer
   x = 1,074.17