Finding the Fourth Proportional to 1,381.61, 1,905.90 and 856.73

Step by Step Solution

1. Step 1: Write the proportion equation
   1,381.61 : 1,905.90 = 856.73 : x
2. Step 2: Convert to fraction form
   1,381.61/1,905.90 = 856.73/x
3. Step 3: Cross multiply
   1,381.61x = 1,905.90 × 856.73
4. Step 4: Simplify right side
   1,381.61x = 1,632,839.77
5. Step 5: Solve for x
   x = 1,632,839.77/1,381.61
6. Step 6: Final answer
   x = 1,181.84