Finding the Fourth Proportional to 1,388.88, 1,916.64 and 799.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.88 : 1,916.64 = 799.40 : x
2. Step 2: Convert to fraction form
   1,388.88/1,916.64 = 799.40/x
3. Step 3: Cross multiply
   1,388.88x = 1,916.64 × 799.40
4. Step 4: Simplify right side
   1,388.88x = 1,532,162.02
5. Step 5: Solve for x
   x = 1,532,162.02/1,388.88
6. Step 6: Final answer
   x = 1,103.16