Finding the Fourth Proportional to 1,078.38, 1,488.34 and 636.39

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.38 : 1,488.34 = 636.39 : x
2. Step 2: Convert to fraction form
   1,078.38/1,488.34 = 636.39/x
3. Step 3: Cross multiply
   1,078.38x = 1,488.34 × 636.39
4. Step 4: Simplify right side
   1,078.38x = 947,164.69
5. Step 5: Solve for x
   x = 947,164.69/1,078.38
6. Step 6: Final answer
   x = 878.32