Finding the Fourth Proportional to 2,147.69, 3,221.49 and 686.81

Step by Step Solution

1. Step 1: Write the proportion equation
   2,147.69 : 3,221.49 = 686.81 : x
2. Step 2: Convert to fraction form
   2,147.69/3,221.49 = 686.81/x
3. Step 3: Cross multiply
   2,147.69x = 3,221.49 × 686.81
4. Step 4: Simplify right side
   2,147.69x = 2,212,551.55
5. Step 5: Solve for x
   x = 2,212,551.55/2,147.69
6. Step 6: Final answer
   x = 1,030.20