Finding the Fourth Proportional to 1,388.71, 1,916.08 and 864.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.71 : 1,916.08 = 864.37 : x
2. Step 2: Convert to fraction form
   1,388.71/1,916.08 = 864.37/x
3. Step 3: Cross multiply
   1,388.71x = 1,916.08 × 864.37
4. Step 4: Simplify right side
   1,388.71x = 1,656,202.07
5. Step 5: Solve for x
   x = 1,656,202.07/1,388.71
6. Step 6: Final answer
   x = 1,192.62