Finding the Fourth Proportional to 1,388.93, 1,916.88 and 791.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.93 : 1,916.88 = 791.57 : x
2. Step 2: Convert to fraction form
   1,388.93/1,916.88 = 791.57/x
3. Step 3: Cross multiply
   1,388.93x = 1,916.88 × 791.57
4. Step 4: Simplify right side
   1,388.93x = 1,517,344.70
5. Step 5: Solve for x
   x = 1,517,344.70/1,388.93
6. Step 6: Final answer
   x = 1,092.46