Finding the Fourth Proportional to 1,379.36, 1,903.56 and 789.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,379.36 : 1,903.56 = 789.80 : x
2. Step 2: Convert to fraction form
   1,379.36/1,903.56 = 789.80/x
3. Step 3: Cross multiply
   1,379.36x = 1,903.56 × 789.80
4. Step 4: Simplify right side
   1,379.36x = 1,503,431.69
5. Step 5: Solve for x
   x = 1,503,431.69/1,379.36
6. Step 6: Final answer
   x = 1,089.95