Finding the Fourth Proportional to 1,081.02, 1,491.73 and 638.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.02 : 1,491.73 = 638.88 : x
2. Step 2: Convert to fraction form
   1,081.02/1,491.73 = 638.88/x
3. Step 3: Cross multiply
   1,081.02x = 1,491.73 × 638.88
4. Step 4: Simplify right side
   1,081.02x = 953,036.46
5. Step 5: Solve for x
   x = 953,036.46/1,081.02
6. Step 6: Final answer
   x = 881.61