Finding the Fourth Proportional to 1,419.20, 1,958.61 and 789.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,419.20 : 1,958.61 = 789.78 : x
2. Step 2: Convert to fraction form
   1,419.20/1,958.61 = 789.78/x
3. Step 3: Cross multiply
   1,419.20x = 1,958.61 × 789.78
4. Step 4: Simplify right side
   1,419.20x = 1,546,881.31
5. Step 5: Solve for x
   x = 1,546,881.31/1,419.20
6. Step 6: Final answer
   x = 1,089.96