Finding the Fourth Proportional to 1,389.47, 1,916.57 and 1,057.16

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.47 : 1,916.57 = 1,057.16 : x
2. Step 2: Convert to fraction form
   1,389.47/1,916.57 = 1,057.16/x
3. Step 3: Cross multiply
   1,389.47x = 1,916.57 × 1,057.16
4. Step 4: Simplify right side
   1,389.47x = 2,026,106.27
5. Step 5: Solve for x
   x = 2,026,106.27/1,389.47
6. Step 6: Final answer
   x = 1,458.19