Finding the Fourth Proportional to 2,665.91, 3,999.29 and 816.89

Step by Step Solution

1. Step 1: Write the proportion equation
   2,665.91 : 3,999.29 = 816.89 : x
2. Step 2: Convert to fraction form
   2,665.91/3,999.29 = 816.89/x
3. Step 3: Cross multiply
   2,665.91x = 3,999.29 × 816.89
4. Step 4: Simplify right side
   2,665.91x = 3,266,955.93
5. Step 5: Solve for x
   x = 3,266,955.93/2,665.91
6. Step 6: Final answer
   x = 1,225.46