Finding the Fourth Proportional to 2,640.18, 3,960.83 and 791.30

Step by Step Solution

1. Step 1: Write the proportion equation
   2,640.18 : 3,960.83 = 791.30 : x
2. Step 2: Convert to fraction form
   2,640.18/3,960.83 = 791.30/x
3. Step 3: Cross multiply
   2,640.18x = 3,960.83 × 791.30
4. Step 4: Simplify right side
   2,640.18x = 3,134,181.02
5. Step 5: Solve for x
   x = 3,134,181.02/2,640.18
6. Step 6: Final answer
   x = 1,187.11