Finding the Fourth Proportional to 1,081.87, 1,493.00 and 639.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.87 : 1,493.00 = 639.61 : x
2. Step 2: Convert to fraction form
   1,081.87/1,493.00 = 639.61/x
3. Step 3: Cross multiply
   1,081.87x = 1,493.00 × 639.61
4. Step 4: Simplify right side
   1,081.87x = 954,935.60
5. Step 5: Solve for x
   x = 954,935.60/1,081.87
6. Step 6: Final answer
   x = 882.67