Finding the Fourth Proportional to 2,790.73, 4,185.64 and 815.89

Step by Step Solution

1. Step 1: Write the proportion equation
   2,790.73 : 4,185.64 = 815.89 : x
2. Step 2: Convert to fraction form
   2,790.73/4,185.64 = 815.89/x
3. Step 3: Cross multiply
   2,790.73x = 4,185.64 × 815.89
4. Step 4: Simplify right side
   2,790.73x = 3,415,017.93
5. Step 5: Solve for x
   x = 3,415,017.93/2,790.73
6. Step 6: Final answer
   x = 1,223.70