Finding the Fourth Proportional to 1,078.86, 1,488.81 and 636.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.86 : 1,488.81 = 636.81 : x
2. Step 2: Convert to fraction form
   1,078.86/1,488.81 = 636.81/x
3. Step 3: Cross multiply
   1,078.86x = 1,488.81 × 636.81
4. Step 4: Simplify right side
   1,078.86x = 948,085.90
5. Step 5: Solve for x
   x = 948,085.90/1,078.86
6. Step 6: Final answer
   x = 878.78