Finding the Fourth Proportional to 1,389.11, 1,916.31 and 857.54

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.11 : 1,916.31 = 857.54 : x
2. Step 2: Convert to fraction form
   1,389.11/1,916.31 = 857.54/x
3. Step 3: Cross multiply
   1,389.11x = 1,916.31 × 857.54
4. Step 4: Simplify right side
   1,389.11x = 1,643,317.27
5. Step 5: Solve for x
   x = 1,643,317.27/1,389.11
6. Step 6: Final answer
   x = 1,183.00