Finding the Fourth Proportional to 2,665.89, 3,998.96 and 816.87

Step by Step Solution

1. Step 1: Write the proportion equation
   2,665.89 : 3,998.96 = 816.87 : x
2. Step 2: Convert to fraction form
   2,665.89/3,998.96 = 816.87/x
3. Step 3: Cross multiply
   2,665.89x = 3,998.96 × 816.87
4. Step 4: Simplify right side
   2,665.89x = 3,266,626.37
5. Step 5: Solve for x
   x = 3,266,626.37/2,665.89
6. Step 6: Final answer
   x = 1,225.34