Finding the Fourth Proportional to 1,377.94, 2,066.31 and 857.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,377.94 : 2,066.31 = 857.15 : x
2. Step 2: Convert to fraction form
   1,377.94/2,066.31 = 857.15/x
3. Step 3: Cross multiply
   1,377.94x = 2,066.31 × 857.15
4. Step 4: Simplify right side
   1,377.94x = 1,771,142.78
5. Step 5: Solve for x
   x = 1,771,142.78/1,377.94
6. Step 6: Final answer
   x = 1,285.36