Finding the Fourth Proportional to 1,305.89, 1,804.59 and 990.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,305.89 : 1,804.59 = 990.59 : x
2. Step 2: Convert to fraction form
   1,305.89/1,804.59 = 990.59/x
3. Step 3: Cross multiply
   1,305.89x = 1,804.59 × 990.59
4. Step 4: Simplify right side
   1,305.89x = 1,787,608.81
5. Step 5: Solve for x
   x = 1,787,608.81/1,305.89
6. Step 6: Final answer
   x = 1,368.88