Finding the Fourth Proportional to 2,113.93, 3,171.17 and 815.77

Step by Step Solution

1. Step 1: Write the proportion equation
   2,113.93 : 3,171.17 = 815.77 : x
2. Step 2: Convert to fraction form
   2,113.93/3,171.17 = 815.77/x
3. Step 3: Cross multiply
   2,113.93x = 3,171.17 × 815.77
4. Step 4: Simplify right side
   2,113.93x = 2,586,941.27
5. Step 5: Solve for x
   x = 2,586,941.27/2,113.93
6. Step 6: Final answer
   x = 1,223.76