Finding the Fourth Proportional to 2,147.05, 3,219.68 and 685.81

Step by Step Solution

1. Step 1: Write the proportion equation
   2,147.05 : 3,219.68 = 685.81 : x
2. Step 2: Convert to fraction form
   2,147.05/3,219.68 = 685.81/x
3. Step 3: Cross multiply
   2,147.05x = 3,219.68 × 685.81
4. Step 4: Simplify right side
   2,147.05x = 2,208,085.31
5. Step 5: Solve for x
   x = 2,208,085.31/2,147.05
6. Step 6: Final answer
   x = 1,028.43