Finding the Fourth Proportional to 1,081.80, 1,492.59 and 639.54

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.80 : 1,492.59 = 639.54 : x
2. Step 2: Convert to fraction form
   1,081.80/1,492.59 = 639.54/x
3. Step 3: Cross multiply
   1,081.80x = 1,492.59 × 639.54
4. Step 4: Simplify right side
   1,081.80x = 954,571.01
5. Step 5: Solve for x
   x = 954,571.01/1,081.80
6. Step 6: Final answer
   x = 882.39