Finding the Fourth Proportional to 1,383.21, 1,908.50 and 858.87

Step by Step Solution

1. Step 1: Write the proportion equation
   1,383.21 : 1,908.50 = 858.87 : x
2. Step 2: Convert to fraction form
   1,383.21/1,908.50 = 858.87/x
3. Step 3: Cross multiply
   1,383.21x = 1,908.50 × 858.87
4. Step 4: Simplify right side
   1,383.21x = 1,639,149.10
5. Step 5: Solve for x
   x = 1,639,149.10/1,383.21
6. Step 6: Final answer
   x = 1,185.03