Finding the Fourth Proportional to 1,078.76, 1,488.57 and 636.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.76 : 1,488.57 = 636.50 : x
2. Step 2: Convert to fraction form
   1,078.76/1,488.57 = 636.50/x
3. Step 3: Cross multiply
   1,078.76x = 1,488.57 × 636.50
4. Step 4: Simplify right side
   1,078.76x = 947,474.81
5. Step 5: Solve for x
   x = 947,474.81/1,078.76
6. Step 6: Final answer
   x = 878.30