Finding the Fourth Proportional to 2,812.79, 4,218.89 and 865.15

Step by Step Solution

1. Step 1: Write the proportion equation
   2,812.79 : 4,218.89 = 865.15 : x
2. Step 2: Convert to fraction form
   2,812.79/4,218.89 = 865.15/x
3. Step 3: Cross multiply
   2,812.79x = 4,218.89 × 865.15
4. Step 4: Simplify right side
   2,812.79x = 3,649,957.81
5. Step 5: Solve for x
   x = 3,649,957.81/2,812.79
6. Step 6: Final answer
   x = 1,297.63