Finding the Fourth Proportional to 1,420.72, 1,960.40 and 791.22

Step by Step Solution

1. Step 1: Write the proportion equation
   1,420.72 : 1,960.40 = 791.22 : x
2. Step 2: Convert to fraction form
   1,420.72/1,960.40 = 791.22/x
3. Step 3: Cross multiply
   1,420.72x = 1,960.40 × 791.22
4. Step 4: Simplify right side
   1,420.72x = 1,551,107.69
5. Step 5: Solve for x
   x = 1,551,107.69/1,420.72
6. Step 6: Final answer
   x = 1,091.78