Finding the Fourth Proportional to 2,820.69, 4,230.78 and 872.91

Step by Step Solution

1. Step 1: Write the proportion equation
   2,820.69 : 4,230.78 = 872.91 : x
2. Step 2: Convert to fraction form
   2,820.69/4,230.78 = 872.91/x
3. Step 3: Cross multiply
   2,820.69x = 4,230.78 × 872.91
4. Step 4: Simplify right side
   2,820.69x = 3,693,090.17
5. Step 5: Solve for x
   x = 3,693,090.17/2,820.69
6. Step 6: Final answer
   x = 1,309.29