Finding the Fourth Proportional to 2,856.10, 4,280.30 and 1,212.21

Step by Step Solution

1. Step 1: Write the proportion equation
   2,856.10 : 4,280.30 = 1,212.21 : x
2. Step 2: Convert to fraction form
   2,856.10/4,280.30 = 1,212.21/x
3. Step 3: Cross multiply
   2,856.10x = 4,280.30 × 1,212.21
4. Step 4: Simplify right side
   2,856.10x = 5,188,622.46
5. Step 5: Solve for x
   x = 5,188,622.46/2,856.10
6. Step 6: Final answer
   x = 1,816.68