Finding the Fourth Proportional to 1,081.35, 1,492.26 and 639.47

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.35 : 1,492.26 = 639.47 : x
2. Step 2: Convert to fraction form
   1,081.35/1,492.26 = 639.47/x
3. Step 3: Cross multiply
   1,081.35x = 1,492.26 × 639.47
4. Step 4: Simplify right side
   1,081.35x = 954,255.50
5. Step 5: Solve for x
   x = 954,255.50/1,081.35
6. Step 6: Final answer
   x = 882.47