Finding the Fourth Proportional to 1,389.50, 1,917.86 and 858.83

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.50 : 1,917.86 = 858.83 : x
2. Step 2: Convert to fraction form
   1,389.50/1,917.86 = 858.83/x
3. Step 3: Cross multiply
   1,389.50x = 1,917.86 × 858.83
4. Step 4: Simplify right side
   1,389.50x = 1,647,116.20
5. Step 5: Solve for x
   x = 1,647,116.20/1,389.50
6. Step 6: Final answer
   x = 1,185.41