Finding the Fourth Proportional to 1,290.50, 1,781.33 and 805.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,290.50 : 1,781.33 = 805.81 : x
2. Step 2: Convert to fraction form
   1,290.50/1,781.33 = 805.81/x
3. Step 3: Cross multiply
   1,290.50x = 1,781.33 × 805.81
4. Step 4: Simplify right side
   1,290.50x = 1,435,413.53
5. Step 5: Solve for x
   x = 1,435,413.53/1,290.50
6. Step 6: Final answer
   x = 1,112.29