Finding the Fourth Proportional to 2,570.29, 3,856.63 and 815.57

Step by Step Solution

1. Step 1: Write the proportion equation
   2,570.29 : 3,856.63 = 815.57 : x
2. Step 2: Convert to fraction form
   2,570.29/3,856.63 = 815.57/x
3. Step 3: Cross multiply
   2,570.29x = 3,856.63 × 815.57
4. Step 4: Simplify right side
   2,570.29x = 3,145,351.73
5. Step 5: Solve for x
   x = 3,145,351.73/2,570.29
6. Step 6: Final answer
   x = 1,223.73