Finding the Fourth Proportional to 1,379.23, 1,903.70 and 789.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,379.23 : 1,903.70 = 789.78 : x
2. Step 2: Convert to fraction form
   1,379.23/1,903.70 = 789.78/x
3. Step 3: Cross multiply
   1,379.23x = 1,903.70 × 789.78
4. Step 4: Simplify right side
   1,379.23x = 1,503,513.30
5. Step 5: Solve for x
   x = 1,503,513.30/1,379.23
6. Step 6: Final answer
   x = 1,090.11