Finding the Fourth Proportional to 1,443.18, 1,991.78 and 813.85

Step by Step Solution

1. Step 1: Write the proportion equation
   1,443.18 : 1,991.78 = 813.85 : x
2. Step 2: Convert to fraction form
   1,443.18/1,991.78 = 813.85/x
3. Step 3: Cross multiply
   1,443.18x = 1,991.78 × 813.85
4. Step 4: Simplify right side
   1,443.18x = 1,621,007.21
5. Step 5: Solve for x
   x = 1,621,007.21/1,443.18
6. Step 6: Final answer
   x = 1,123.22