Finding the Fourth Proportional to 1,080.96, 1,491.33 and 638.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.96 : 1,491.33 = 638.81 : x
2. Step 2: Convert to fraction form
   1,080.96/1,491.33 = 638.81/x
3. Step 3: Cross multiply
   1,080.96x = 1,491.33 × 638.81
4. Step 4: Simplify right side
   1,080.96x = 952,676.52
5. Step 5: Solve for x
   x = 952,676.52/1,080.96
6. Step 6: Final answer
   x = 881.32