Finding the Fourth Proportional to 1,388.04, 1,916.04 and 864.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.04 : 1,916.04 = 864.40 : x
2. Step 2: Convert to fraction form
   1,388.04/1,916.04 = 864.40/x
3. Step 3: Cross multiply
   1,388.04x = 1,916.04 × 864.40
4. Step 4: Simplify right side
   1,388.04x = 1,656,224.98
5. Step 5: Solve for x
   x = 1,656,224.98/1,388.04
6. Step 6: Final answer
   x = 1,193.21