Finding the Fourth Proportional to 1,290.94, 1,780.84 and 818.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,290.94 : 1,780.84 = 818.05 : x
2. Step 2: Convert to fraction form
   1,290.94/1,780.84 = 818.05/x
3. Step 3: Cross multiply
   1,290.94x = 1,780.84 × 818.05
4. Step 4: Simplify right side
   1,290.94x = 1,456,816.16
5. Step 5: Solve for x
   x = 1,456,816.16/1,290.94
6. Step 6: Final answer
   x = 1,128.49