Finding the Fourth Proportional to 1,078.86, 1,488.96 and 636.75

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.86 : 1,488.96 = 636.75 : x
2. Step 2: Convert to fraction form
   1,078.86/1,488.96 = 636.75/x
3. Step 3: Cross multiply
   1,078.86x = 1,488.96 × 636.75
4. Step 4: Simplify right side
   1,078.86x = 948,095.28
5. Step 5: Solve for x
   x = 948,095.28/1,078.86
6. Step 6: Final answer
   x = 878.79