Finding the Fourth Proportional to 2,155.92, 3,231.18 and 921.89

Step by Step Solution

1. Step 1: Write the proportion equation
   2,155.92 : 3,231.18 = 921.89 : x
2. Step 2: Convert to fraction form
   2,155.92/3,231.18 = 921.89/x
3. Step 3: Cross multiply
   2,155.92x = 3,231.18 × 921.89
4. Step 4: Simplify right side
   2,155.92x = 2,978,792.53
5. Step 5: Solve for x
   x = 2,978,792.53/2,155.92
6. Step 6: Final answer
   x = 1,381.68