Finding the Fourth Proportional to 1,369.94, 1,890.42 and 780.36

Step by Step Solution

1. Step 1: Write the proportion equation
   1,369.94 : 1,890.42 = 780.36 : x
2. Step 2: Convert to fraction form
   1,369.94/1,890.42 = 780.36/x
3. Step 3: Cross multiply
   1,369.94x = 1,890.42 × 780.36
4. Step 4: Simplify right side
   1,369.94x = 1,475,208.15
5. Step 5: Solve for x
   x = 1,475,208.15/1,369.94
6. Step 6: Final answer
   x = 1,076.84