Finding the Fourth Proportional to 1,443.11, 1,991.55 and 813.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,443.11 : 1,991.55 = 813.61 : x
2. Step 2: Convert to fraction form
   1,443.11/1,991.55 = 813.61/x
3. Step 3: Cross multiply
   1,443.11x = 1,991.55 × 813.61
4. Step 4: Simplify right side
   1,443.11x = 1,620,345.00
5. Step 5: Solve for x
   x = 1,620,345.00/1,443.11
6. Step 6: Final answer
   x = 1,122.81