Finding the Fourth Proportional to 1,081.53, 1,492.25 and 639.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.53 : 1,492.25 = 639.18 : x
2. Step 2: Convert to fraction form
   1,081.53/1,492.25 = 639.18/x
3. Step 3: Cross multiply
   1,081.53x = 1,492.25 × 639.18
4. Step 4: Simplify right side
   1,081.53x = 953,813.16
5. Step 5: Solve for x
   x = 953,813.16/1,081.53
6. Step 6: Final answer
   x = 881.91