Finding the Fourth Proportional to 1,420.78, 1,960.54 and 791.23

Step by Step Solution

1. Step 1: Write the proportion equation
   1,420.78 : 1,960.54 = 791.23 : x
2. Step 2: Convert to fraction form
   1,420.78/1,960.54 = 791.23/x
3. Step 3: Cross multiply
   1,420.78x = 1,960.54 × 791.23
4. Step 4: Simplify right side
   1,420.78x = 1,551,234.86
5. Step 5: Solve for x
   x = 1,551,234.86/1,420.78
6. Step 6: Final answer
   x = 1,091.82