Finding the Fourth Proportional to 1,057.57, 1,585.40 and 408.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,057.57 : 1,585.40 = 408.15 : x
2. Step 2: Convert to fraction form
   1,057.57/1,585.40 = 408.15/x
3. Step 3: Cross multiply
   1,057.57x = 1,585.40 × 408.15
4. Step 4: Simplify right side
   1,057.57x = 647,081.01
5. Step 5: Solve for x
   x = 647,081.01/1,057.57
6. Step 6: Final answer
   x = 611.86