Finding the Fourth Proportional to 1,078.89, 1,488.61 and 780.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.89 : 1,488.61 = 780.57 : x
2. Step 2: Convert to fraction form
   1,078.89/1,488.61 = 780.57/x
3. Step 3: Cross multiply
   1,078.89x = 1,488.61 × 780.57
4. Step 4: Simplify right side
   1,078.89x = 1,161,965.28
5. Step 5: Solve for x
   x = 1,161,965.28/1,078.89
6. Step 6: Final answer
   x = 1,077.00