Finding the Fourth Proportional to 1,081.73, 1,493.15 and 639.60

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.73 : 1,493.15 = 639.60 : x
2. Step 2: Convert to fraction form
   1,081.73/1,493.15 = 639.60/x
3. Step 3: Cross multiply
   1,081.73x = 1,493.15 × 639.60
4. Step 4: Simplify right side
   1,081.73x = 955,015.54
5. Step 5: Solve for x
   x = 955,015.54/1,081.73
6. Step 6: Final answer
   x = 882.86