Finding the Fourth Proportional to 1,388.41, 1,916.05 and 857.32

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.41 : 1,916.05 = 857.32 : x
2. Step 2: Convert to fraction form
   1,388.41/1,916.05 = 857.32/x
3. Step 3: Cross multiply
   1,388.41x = 1,916.05 × 857.32
4. Step 4: Simplify right side
   1,388.41x = 1,642,662.66
5. Step 5: Solve for x
   x = 1,642,662.66/1,388.41
6. Step 6: Final answer
   x = 1,183.12