Finding the Fourth Proportional to 1,201.89, 1,800.50 and 789.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,201.89 : 1,800.50 = 789.78 : x
2. Step 2: Convert to fraction form
   1,201.89/1,800.50 = 789.78/x
3. Step 3: Cross multiply
   1,201.89x = 1,800.50 × 789.78
4. Step 4: Simplify right side
   1,201.89x = 1,421,998.89
5. Step 5: Solve for x
   x = 1,421,998.89/1,201.89
6. Step 6: Final answer
   x = 1,183.14