Finding the Fourth Proportional to 1,388.37, 1,916.16 and 864.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.37 : 1,916.16 = 864.57 : x
2. Step 2: Convert to fraction form
   1,388.37/1,916.16 = 864.57/x
3. Step 3: Cross multiply
   1,388.37x = 1,916.16 × 864.57
4. Step 4: Simplify right side
   1,388.37x = 1,656,654.45
5. Step 5: Solve for x
   x = 1,656,654.45/1,388.37
6. Step 6: Final answer
   x = 1,193.24