Finding the Fourth Proportional to 2,659.30, 3,989.80 and 810.77

Step by Step Solution

1. Step 1: Write the proportion equation
   2,659.30 : 3,989.80 = 810.77 : x
2. Step 2: Convert to fraction form
   2,659.30/3,989.80 = 810.77/x
3. Step 3: Cross multiply
   2,659.30x = 3,989.80 × 810.77
4. Step 4: Simplify right side
   2,659.30x = 3,234,810.15
5. Step 5: Solve for x
   x = 3,234,810.15/2,659.30
6. Step 6: Final answer
   x = 1,216.41