Finding the Fourth Proportional to 1,420.72, 1,960.56 and 791.28

Step by Step Solution

1. Step 1: Write the proportion equation
   1,420.72 : 1,960.56 = 791.28 : x
2. Step 2: Convert to fraction form
   1,420.72/1,960.56 = 791.28/x
3. Step 3: Cross multiply
   1,420.72x = 1,960.56 × 791.28
4. Step 4: Simplify right side
   1,420.72x = 1,551,351.92
5. Step 5: Solve for x
   x = 1,551,351.92/1,420.72
6. Step 6: Final answer
   x = 1,091.95