Finding the Fourth Proportional to 1,381.78, 1,906.14 and 856.90

Step by Step Solution

1. Step 1: Write the proportion equation
   1,381.78 : 1,906.14 = 856.90 : x
2. Step 2: Convert to fraction form
   1,381.78/1,906.14 = 856.90/x
3. Step 3: Cross multiply
   1,381.78x = 1,906.14 × 856.90
4. Step 4: Simplify right side
   1,381.78x = 1,633,371.37
5. Step 5: Solve for x
   x = 1,633,371.37/1,381.78
6. Step 6: Final answer
   x = 1,182.08