Finding the Fourth Proportional to 1,389.96, 1,917.27 and 858.70

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.96 : 1,917.27 = 858.70 : x
2. Step 2: Convert to fraction form
   1,389.96/1,917.27 = 858.70/x
3. Step 3: Cross multiply
   1,389.96x = 1,917.27 × 858.70
4. Step 4: Simplify right side
   1,389.96x = 1,646,362.15
5. Step 5: Solve for x
   x = 1,646,362.15/1,389.96
6. Step 6: Final answer
   x = 1,184.47