Finding the Fourth Proportional to 1,081.96, 1,492.72 and 639.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.96 : 1,492.72 = 639.77 : x
2. Step 2: Convert to fraction form
   1,081.96/1,492.72 = 639.77/x
3. Step 3: Cross multiply
   1,081.96x = 1,492.72 × 639.77
4. Step 4: Simplify right side
   1,081.96x = 954,988.41
5. Step 5: Solve for x
   x = 954,988.41/1,081.96
6. Step 6: Final answer
   x = 882.65