Finding the Fourth Proportional to 1,443.38, 1,991.70 and 813.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,443.38 : 1,991.70 = 813.89 : x
2. Step 2: Convert to fraction form
   1,443.38/1,991.70 = 813.89/x
3. Step 3: Cross multiply
   1,443.38x = 1,991.70 × 813.89
4. Step 4: Simplify right side
   1,443.38x = 1,621,014.75
5. Step 5: Solve for x
   x = 1,621,014.75/1,443.38
6. Step 6: Final answer
   x = 1,123.07