Finding the Fourth Proportional to 1,378.85, 1,902.79 and 789.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,378.85 : 1,902.79 = 789.43 : x
2. Step 2: Convert to fraction form
   1,378.85/1,902.79 = 789.43/x
3. Step 3: Cross multiply
   1,378.85x = 1,902.79 × 789.43
4. Step 4: Simplify right side
   1,378.85x = 1,502,112.78
5. Step 5: Solve for x
   x = 1,502,112.78/1,378.85
6. Step 6: Final answer
   x = 1,089.39