Finding the Fourth Proportional to 1,078.65, 1,488.83 and 636.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.65 : 1,488.83 = 636.71 : x
2. Step 2: Convert to fraction form
   1,078.65/1,488.83 = 636.71/x
3. Step 3: Cross multiply
   1,078.65x = 1,488.83 × 636.71
4. Step 4: Simplify right side
   1,078.65x = 947,942.32
5. Step 5: Solve for x
   x = 947,942.32/1,078.65
6. Step 6: Final answer
   x = 878.82