Finding the Fourth Proportional to 2,570.31, 3,855.33 and 815.22

Step by Step Solution

1. Step 1: Write the proportion equation
   2,570.31 : 3,855.33 = 815.22 : x
2. Step 2: Convert to fraction form
   2,570.31/3,855.33 = 815.22/x
3. Step 3: Cross multiply
   2,570.31x = 3,855.33 × 815.22
4. Step 4: Simplify right side
   2,570.31x = 3,142,942.12
5. Step 5: Solve for x
   x = 3,142,942.12/2,570.31
6. Step 6: Final answer
   x = 1,222.79