Finding the Fourth Proportional to 2,086.55, 3,129.72 and 699.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,086.55 : 3,129.72 = 699.78 : x
2. Step 2: Convert to fraction form
   2,086.55/3,129.72 = 699.78/x
3. Step 3: Cross multiply
   2,086.55x = 3,129.72 × 699.78
4. Step 4: Simplify right side
   2,086.55x = 2,190,104.39
5. Step 5: Solve for x
   x = 2,190,104.39/2,086.55
6. Step 6: Final answer
   x = 1,049.63