Finding the Fourth Proportional to 2,559.78, 3,840.42 and 828.36

Step by Step Solution

1. Step 1: Write the proportion equation
   2,559.78 : 3,840.42 = 828.36 : x
2. Step 2: Convert to fraction form
   2,559.78/3,840.42 = 828.36/x
3. Step 3: Cross multiply
   2,559.78x = 3,840.42 × 828.36
4. Step 4: Simplify right side
   2,559.78x = 3,181,250.31
5. Step 5: Solve for x
   x = 3,181,250.31/2,559.78
6. Step 6: Final answer
   x = 1,242.78