Finding the Fourth Proportional to 2,856.61, 4,285.57 and 1,213.21

Step by Step Solution

1. Step 1: Write the proportion equation
   2,856.61 : 4,285.57 = 1,213.21 : x
2. Step 2: Convert to fraction form
   2,856.61/4,285.57 = 1,213.21/x
3. Step 3: Cross multiply
   2,856.61x = 4,285.57 × 1,213.21
4. Step 4: Simplify right side
   2,856.61x = 5,199,296.38
5. Step 5: Solve for x
   x = 5,199,296.38/2,856.61
6. Step 6: Final answer
   x = 1,820.09