Finding the Fourth Proportional to 2,790.75, 4,185.72 and 815.86

Step by Step Solution

1. Step 1: Write the proportion equation
   2,790.75 : 4,185.72 = 815.86 : x
2. Step 2: Convert to fraction form
   2,790.75/4,185.72 = 815.86/x
3. Step 3: Cross multiply
   2,790.75x = 4,185.72 × 815.86
4. Step 4: Simplify right side
   2,790.75x = 3,414,961.52
5. Step 5: Solve for x
   x = 3,414,961.52/2,790.75
6. Step 6: Final answer
   x = 1,223.67