Finding the Fourth Proportional to 2,090.78, 3,136.98 and 858.77

Step by Step Solution

1. Step 1: Write the proportion equation
   2,090.78 : 3,136.98 = 858.77 : x
2. Step 2: Convert to fraction form
   2,090.78/3,136.98 = 858.77/x
3. Step 3: Cross multiply
   2,090.78x = 3,136.98 × 858.77
4. Step 4: Simplify right side
   2,090.78x = 2,693,944.31
5. Step 5: Solve for x
   x = 2,693,944.31/2,090.78
6. Step 6: Final answer
   x = 1,288.49