Finding the Fourth Proportional to 2,576.71, 3,865.37 and 821.10

Step by Step Solution

1. Step 1: Write the proportion equation
   2,576.71 : 3,865.37 = 821.10 : x
2. Step 2: Convert to fraction form
   2,576.71/3,865.37 = 821.10/x
3. Step 3: Cross multiply
   2,576.71x = 3,865.37 × 821.10
4. Step 4: Simplify right side
   2,576.71x = 3,173,851.20
5. Step 5: Solve for x
   x = 3,173,851.20/2,576.71
6. Step 6: Final answer
   x = 1,231.75