Finding the Fourth Proportional to 1,081.38, 1,491.82 and 639.29

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.38 : 1,491.82 = 639.29 : x
2. Step 2: Convert to fraction form
   1,081.38/1,491.82 = 639.29/x
3. Step 3: Cross multiply
   1,081.38x = 1,491.82 × 639.29
4. Step 4: Simplify right side
   1,081.38x = 953,707.74
5. Step 5: Solve for x
   x = 953,707.74/1,081.38
6. Step 6: Final answer
   x = 881.93