Finding the Fourth Proportional to 1,078.67, 1,488.81 and 636.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.67 : 1,488.81 = 636.72 : x
2. Step 2: Convert to fraction form
   1,078.67/1,488.81 = 636.72/x
3. Step 3: Cross multiply
   1,078.67x = 1,488.81 × 636.72
4. Step 4: Simplify right side
   1,078.67x = 947,955.10
5. Step 5: Solve for x
   x = 947,955.10/1,078.67
6. Step 6: Final answer
   x = 878.82