Finding the Fourth Proportional to 1,388.55, 1,916.60 and 799.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.55 : 1,916.60 = 799.50 : x
2. Step 2: Convert to fraction form
   1,388.55/1,916.60 = 799.50/x
3. Step 3: Cross multiply
   1,388.55x = 1,916.60 × 799.50
4. Step 4: Simplify right side
   1,388.55x = 1,532,314.12
5. Step 5: Solve for x
   x = 1,532,314.12/1,388.55
6. Step 6: Final answer
   x = 1,103.54