Finding the Fourth Proportional to 1,378.98, 1,902.42 and 789.39

Step by Step Solution

1. Step 1: Write the proportion equation
   1,378.98 : 1,902.42 = 789.39 : x
2. Step 2: Convert to fraction form
   1,378.98/1,902.42 = 789.39/x
3. Step 3: Cross multiply
   1,378.98x = 1,902.42 × 789.39
4. Step 4: Simplify right side
   1,378.98x = 1,501,751.32
5. Step 5: Solve for x
   x = 1,501,751.32/1,378.98
6. Step 6: Final answer
   x = 1,089.03