Finding the Fourth Proportional to 1,381.90, 1,906.31 and 857.02

Step by Step Solution

1. Step 1: Write the proportion equation
   1,381.90 : 1,906.31 = 857.02 : x
2. Step 2: Convert to fraction form
   1,381.90/1,906.31 = 857.02/x
3. Step 3: Cross multiply
   1,381.90x = 1,906.31 × 857.02
4. Step 4: Simplify right side
   1,381.90x = 1,633,745.80
5. Step 5: Solve for x
   x = 1,633,745.80/1,381.90
6. Step 6: Final answer
   x = 1,182.25