Finding the Fourth Proportional to 2,661.72, 3,992.56 and 813.04

Step by Step Solution

1. Step 1: Write the proportion equation
   2,661.72 : 3,992.56 = 813.04 : x
2. Step 2: Convert to fraction form
   2,661.72/3,992.56 = 813.04/x
3. Step 3: Cross multiply
   2,661.72x = 3,992.56 × 813.04
4. Step 4: Simplify right side
   2,661.72x = 3,246,110.98
5. Step 5: Solve for x
   x = 3,246,110.98/2,661.72
6. Step 6: Final answer
   x = 1,219.55