Finding the Fourth Proportional to 2,105.72, 3,159.03 and 807.20

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.72 : 3,159.03 = 807.20 : x
2. Step 2: Convert to fraction form
   2,105.72/3,159.03 = 807.20/x
3. Step 3: Cross multiply
   2,105.72x = 3,159.03 × 807.20
4. Step 4: Simplify right side
   2,105.72x = 2,549,953.22
5. Step 5: Solve for x
   x = 2,549,953.22/2,105.72
6. Step 6: Final answer
   x = 1,210.97