Finding the Fourth Proportional to 2,215.78, 3,323.59 and 828.55

Step by Step Solution

1. Step 1: Write the proportion equation
   2,215.78 : 3,323.59 = 828.55 : x
2. Step 2: Convert to fraction form
   2,215.78/3,323.59 = 828.55/x
3. Step 3: Cross multiply
   2,215.78x = 3,323.59 × 828.55
4. Step 4: Simplify right side
   2,215.78x = 2,753,760.49
5. Step 5: Solve for x
   x = 2,753,760.49/2,215.78
6. Step 6: Final answer
   x = 1,242.80