Finding the Fourth Proportional to 2,011.78, 3,018.84 and 857.50

Step by Step Solution

1. Step 1: Write the proportion equation
   2,011.78 : 3,018.84 = 857.50 : x
2. Step 2: Convert to fraction form
   2,011.78/3,018.84 = 857.50/x
3. Step 3: Cross multiply
   2,011.78x = 3,018.84 × 857.50
4. Step 4: Simplify right side
   2,011.78x = 2,588,655.30
5. Step 5: Solve for x
   x = 2,588,655.30/2,011.78
6. Step 6: Final answer
   x = 1,286.75