Finding the Fourth Proportional to 1,385.78, 1,912.18 and 796.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.78 : 1,912.18 = 796.21 : x
2. Step 2: Convert to fraction form
   1,385.78/1,912.18 = 796.21/x
3. Step 3: Cross multiply
   1,385.78x = 1,912.18 × 796.21
4. Step 4: Simplify right side
   1,385.78x = 1,522,490.07
5. Step 5: Solve for x
   x = 1,522,490.07/1,385.78
6. Step 6: Final answer
   x = 1,098.65