Finding the Fourth Proportional to 1,388.97, 1,916.35 and 791.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.97 : 1,916.35 = 791.42 : x
2. Step 2: Convert to fraction form
   1,388.97/1,916.35 = 791.42/x
3. Step 3: Cross multiply
   1,388.97x = 1,916.35 × 791.42
4. Step 4: Simplify right side
   1,388.97x = 1,516,637.72
5. Step 5: Solve for x
   x = 1,516,637.72/1,388.97
6. Step 6: Final answer
   x = 1,091.92