Finding the Fourth Proportional to 1,389.36, 1,916.90 and 799.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.36 : 1,916.90 = 799.78 : x
2. Step 2: Convert to fraction form
   1,389.36/1,916.90 = 799.78/x
3. Step 3: Cross multiply
   1,389.36x = 1,916.90 × 799.78
4. Step 4: Simplify right side
   1,389.36x = 1,533,098.28
5. Step 5: Solve for x
   x = 1,533,098.28/1,389.36
6. Step 6: Final answer
   x = 1,103.46