Finding the Fourth Proportional to 1,081.37, 1,492.70 and 639.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.37 : 1,492.70 = 639.43 : x
2. Step 2: Convert to fraction form
   1,081.37/1,492.70 = 639.43/x
3. Step 3: Cross multiply
   1,081.37x = 1,492.70 × 639.43
4. Step 4: Simplify right side
   1,081.37x = 954,470.23
5. Step 5: Solve for x
   x = 954,470.23/1,081.37
6. Step 6: Final answer
   x = 882.65