Finding the Fourth Proportional to 1,322.42, 1,986.51 and 809.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,322.42 : 1,986.51 = 809.78 : x
2. Step 2: Convert to fraction form
   1,322.42/1,986.51 = 809.78/x
3. Step 3: Cross multiply
   1,322.42x = 1,986.51 × 809.78
4. Step 4: Simplify right side
   1,322.42x = 1,608,636.07
5. Step 5: Solve for x
   x = 1,608,636.07/1,322.42
6. Step 6: Final answer
   x = 1,216.43