Finding the Fourth Proportional to 1,078.88, 1,488.12 and 636.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.88 : 1,488.12 = 636.80 : x
2. Step 2: Convert to fraction form
   1,078.88/1,488.12 = 636.80/x
3. Step 3: Cross multiply
   1,078.88x = 1,488.12 × 636.80
4. Step 4: Simplify right side
   1,078.88x = 947,634.82
5. Step 5: Solve for x
   x = 947,634.82/1,078.88
6. Step 6: Final answer
   x = 878.35