Finding the Fourth Proportional to 1,388.98, 1,916.87 and 799.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.98 : 1,916.87 = 799.61 : x
2. Step 2: Convert to fraction form
   1,388.98/1,916.87 = 799.61/x
3. Step 3: Cross multiply
   1,388.98x = 1,916.87 × 799.61
4. Step 4: Simplify right side
   1,388.98x = 1,532,748.42
5. Step 5: Solve for x
   x = 1,532,748.42/1,388.98
6. Step 6: Final answer
   x = 1,103.51