Finding the Fourth Proportional to 2,640.32, 3,959.31 and 791.09

Step by Step Solution

1. Step 1: Write the proportion equation
   2,640.32 : 3,959.31 = 791.09 : x
2. Step 2: Convert to fraction form
   2,640.32/3,959.31 = 791.09/x
3. Step 3: Cross multiply
   2,640.32x = 3,959.31 × 791.09
4. Step 4: Simplify right side
   2,640.32x = 3,132,173.03
5. Step 5: Solve for x
   x = 3,132,173.03/2,640.32
6. Step 6: Final answer
   x = 1,186.28