Finding the Fourth Proportional to 1,419.21, 1,958.51 and 789.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,419.21 : 1,958.51 = 789.80 : x
2. Step 2: Convert to fraction form
   1,419.21/1,958.51 = 789.80/x
3. Step 3: Cross multiply
   1,419.21x = 1,958.51 × 789.80
4. Step 4: Simplify right side
   1,419.21x = 1,546,817.46
5. Step 5: Solve for x
   x = 1,546,817.46/1,419.21
6. Step 6: Final answer
   x = 1,089.91