Finding the Fourth Proportional to 1,399.47, 1,931.36 and 778.47

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.47 : 1,931.36 = 778.47 : x
2. Step 2: Convert to fraction form
   1,399.47/1,931.36 = 778.47/x
3. Step 3: Cross multiply
   1,399.47x = 1,931.36 × 778.47
4. Step 4: Simplify right side
   1,399.47x = 1,503,501.93
5. Step 5: Solve for x
   x = 1,503,501.93/1,399.47
6. Step 6: Final answer
   x = 1,074.34