Finding the Fourth Proportional to 2,587.02, 3,880.59 and 855.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,587.02 : 3,880.59 = 855.78 : x
2. Step 2: Convert to fraction form
   2,587.02/3,880.59 = 855.78/x
3. Step 3: Cross multiply
   2,587.02x = 3,880.59 × 855.78
4. Step 4: Simplify right side
   2,587.02x = 3,320,931.31
5. Step 5: Solve for x
   x = 3,320,931.31/2,587.02
6. Step 6: Final answer
   x = 1,283.69