Finding the Fourth Proportional to 1,389.16, 1,916.32 and 1,057.04

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.16 : 1,916.32 = 1,057.04 : x
2. Step 2: Convert to fraction form
   1,389.16/1,916.32 = 1,057.04/x
3. Step 3: Cross multiply
   1,389.16x = 1,916.32 × 1,057.04
4. Step 4: Simplify right side
   1,389.16x = 2,025,626.89
5. Step 5: Solve for x
   x = 2,025,626.89/1,389.16
6. Step 6: Final answer
   x = 1,458.17