Finding the Fourth Proportional to 1,388.43, 1,916.15 and 864.54

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.43 : 1,916.15 = 864.54 : x
2. Step 2: Convert to fraction form
   1,388.43/1,916.15 = 864.54/x
3. Step 3: Cross multiply
   1,388.43x = 1,916.15 × 864.54
4. Step 4: Simplify right side
   1,388.43x = 1,656,588.32
5. Step 5: Solve for x
   x = 1,656,588.32/1,388.43
6. Step 6: Final answer
   x = 1,193.14