Finding the Fourth Proportional to 1,081.58, 1,492.60 and 639.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.58 : 1,492.60 = 639.56 : x
2. Step 2: Convert to fraction form
   1,081.58/1,492.60 = 639.56/x
3. Step 3: Cross multiply
   1,081.58x = 1,492.60 × 639.56
4. Step 4: Simplify right side
   1,081.58x = 954,608.85
5. Step 5: Solve for x
   x = 954,608.85/1,081.58
6. Step 6: Final answer
   x = 882.60