Finding the Fourth Proportional to 1,378.60, 1,902.06 and 789.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,378.60 : 1,902.06 = 789.12 : x
2. Step 2: Convert to fraction form
   1,378.60/1,902.06 = 789.12/x
3. Step 3: Cross multiply
   1,378.60x = 1,902.06 × 789.12
4. Step 4: Simplify right side
   1,378.60x = 1,500,953.59
5. Step 5: Solve for x
   x = 1,500,953.59/1,378.60
6. Step 6: Final answer
   x = 1,088.75