Finding the Fourth Proportional to 1,320.72, 1,822.41 and 789.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,320.72 : 1,822.41 = 789.57 : x
2. Step 2: Convert to fraction form
   1,320.72/1,822.41 = 789.57/x
3. Step 3: Cross multiply
   1,320.72x = 1,822.41 × 789.57
4. Step 4: Simplify right side
   1,320.72x = 1,438,920.26
5. Step 5: Solve for x
   x = 1,438,920.26/1,320.72
6. Step 6: Final answer
   x = 1,089.50