Finding the Fourth Proportional to 2,145.69, 3,218.49 and 684.81

Step by Step Solution

1. Step 1: Write the proportion equation
   2,145.69 : 3,218.49 = 684.81 : x
2. Step 2: Convert to fraction form
   2,145.69/3,218.49 = 684.81/x
3. Step 3: Cross multiply
   2,145.69x = 3,218.49 × 684.81
4. Step 4: Simplify right side
   2,145.69x = 2,204,054.14
5. Step 5: Solve for x
   x = 2,204,054.14/2,145.69
6. Step 6: Final answer
   x = 1,027.20