Finding the Fourth Proportional to 2,086.77, 3,128.31 and 789.15

Step by Step Solution

1. Step 1: Write the proportion equation
   2,086.77 : 3,128.31 = 789.15 : x
2. Step 2: Convert to fraction form
   2,086.77/3,128.31 = 789.15/x
3. Step 3: Cross multiply
   2,086.77x = 3,128.31 × 789.15
4. Step 4: Simplify right side
   2,086.77x = 2,468,705.84
5. Step 5: Solve for x
   x = 2,468,705.84/2,086.77
6. Step 6: Final answer
   x = 1,183.03