Finding the Fourth Proportional to 1,078.60, 1,488.28 and 636.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.60 : 1,488.28 = 636.88 : x
2. Step 2: Convert to fraction form
   1,078.60/1,488.28 = 636.88/x
3. Step 3: Cross multiply
   1,078.60x = 1,488.28 × 636.88
4. Step 4: Simplify right side
   1,078.60x = 947,855.77
5. Step 5: Solve for x
   x = 947,855.77/1,078.60
6. Step 6: Final answer
   x = 878.78