Finding the Fourth Proportional to 1,355.86, 1,870.38 and 857.64

Step by Step Solution

1. Step 1: Write the proportion equation
   1,355.86 : 1,870.38 = 857.64 : x
2. Step 2: Convert to fraction form
   1,355.86/1,870.38 = 857.64/x
3. Step 3: Cross multiply
   1,355.86x = 1,870.38 × 857.64
4. Step 4: Simplify right side
   1,355.86x = 1,604,112.70
5. Step 5: Solve for x
   x = 1,604,112.70/1,355.86
6. Step 6: Final answer
   x = 1,183.10