Finding the Fourth Proportional to 1,078.45, 1,488.17 and 636.39

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.45 : 1,488.17 = 636.39 : x
2. Step 2: Convert to fraction form
   1,078.45/1,488.17 = 636.39/x
3. Step 3: Cross multiply
   1,078.45x = 1,488.17 × 636.39
4. Step 4: Simplify right side
   1,078.45x = 947,058.10
5. Step 5: Solve for x
   x = 947,058.10/1,078.45
6. Step 6: Final answer
   x = 878.17