Finding the Fourth Proportional to 1,388.37, 1,916.47 and 864.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.37 : 1,916.47 = 864.30 : x
2. Step 2: Convert to fraction form
   1,388.37/1,916.47 = 864.30/x
3. Step 3: Cross multiply
   1,388.37x = 1,916.47 × 864.30
4. Step 4: Simplify right side
   1,388.37x = 1,656,405.02
5. Step 5: Solve for x
   x = 1,656,405.02/1,388.37
6. Step 6: Final answer
   x = 1,193.06