Finding the Fourth Proportional to 1,081.98, 1,493.06 and 639.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.98 : 1,493.06 = 639.77 : x
2. Step 2: Convert to fraction form
   1,081.98/1,493.06 = 639.77/x
3. Step 3: Cross multiply
   1,081.98x = 1,493.06 × 639.77
4. Step 4: Simplify right side
   1,081.98x = 955,204.33
5. Step 5: Solve for x
   x = 955,204.33/1,081.98
6. Step 6: Final answer
   x = 882.83