Finding the Fourth Proportional to 2,662.35, 3,991.86 and 812.85

Step by Step Solution

1. Step 1: Write the proportion equation
   2,662.35 : 3,991.86 = 812.85 : x
2. Step 2: Convert to fraction form
   2,662.35/3,991.86 = 812.85/x
3. Step 3: Cross multiply
   2,662.35x = 3,991.86 × 812.85
4. Step 4: Simplify right side
   2,662.35x = 3,244,783.40
5. Step 5: Solve for x
   x = 3,244,783.40/2,662.35
6. Step 6: Final answer
   x = 1,218.77