Finding the Fourth Proportional to 2,111.73, 3,168.05 and 813.20

Step by Step Solution

1. Step 1: Write the proportion equation
   2,111.73 : 3,168.05 = 813.20 : x
2. Step 2: Convert to fraction form
   2,111.73/3,168.05 = 813.20/x
3. Step 3: Cross multiply
   2,111.73x = 3,168.05 × 813.20
4. Step 4: Simplify right side
   2,111.73x = 2,576,258.26
5. Step 5: Solve for x
   x = 2,576,258.26/2,111.73
6. Step 6: Final answer
   x = 1,219.98