Finding the Fourth Proportional to 1,378.50, 1,902.30 and 789.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,378.50 : 1,902.30 = 789.10 : x
2. Step 2: Convert to fraction form
   1,378.50/1,902.30 = 789.10/x
3. Step 3: Cross multiply
   1,378.50x = 1,902.30 × 789.10
4. Step 4: Simplify right side
   1,378.50x = 1,501,104.93
5. Step 5: Solve for x
   x = 1,501,104.93/1,378.50
6. Step 6: Final answer
   x = 1,088.94