Finding the Fourth Proportional to 1,078.87, 1,488.82 and 636.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.87 : 1,488.82 = 636.81 : x
2. Step 2: Convert to fraction form
   1,078.87/1,488.82 = 636.81/x
3. Step 3: Cross multiply
   1,078.87x = 1,488.82 × 636.81
4. Step 4: Simplify right side
   1,078.87x = 948,095.46
5. Step 5: Solve for x
   x = 948,095.46/1,078.87
6. Step 6: Final answer
   x = 878.79