Finding the Fourth Proportional to 1,378.66, 1,902.68 and 789.28

Step by Step Solution

1. Step 1: Write the proportion equation
   1,378.66 : 1,902.68 = 789.28 : x
2. Step 2: Convert to fraction form
   1,378.66/1,902.68 = 789.28/x
3. Step 3: Cross multiply
   1,378.66x = 1,902.68 × 789.28
4. Step 4: Simplify right side
   1,378.66x = 1,501,747.27
5. Step 5: Solve for x
   x = 1,501,747.27/1,378.66
6. Step 6: Final answer
   x = 1,089.28