Finding the Fourth Proportional to 1,388.76, 1,916.10 and 791.27

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.76 : 1,916.10 = 791.27 : x
2. Step 2: Convert to fraction form
   1,388.76/1,916.10 = 791.27/x
3. Step 3: Cross multiply
   1,388.76x = 1,916.10 × 791.27
4. Step 4: Simplify right side
   1,388.76x = 1,516,142.87
5. Step 5: Solve for x
   x = 1,516,142.87/1,388.76
6. Step 6: Final answer
   x = 1,091.72