Finding the Fourth Proportional to 2,105.82, 3,158.64 and 807.21

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.82 : 3,158.64 = 807.21 : x
2. Step 2: Convert to fraction form
   2,105.82/3,158.64 = 807.21/x
3. Step 3: Cross multiply
   2,105.82x = 3,158.64 × 807.21
4. Step 4: Simplify right side
   2,105.82x = 2,549,685.79
5. Step 5: Solve for x
   x = 2,549,685.79/2,105.82
6. Step 6: Final answer
   x = 1,210.78