Finding the Fourth Proportional to 1,162.79, 1,604.56 and 638.85

Step by Step Solution

1. Step 1: Write the proportion equation
   1,162.79 : 1,604.56 = 638.85 : x
2. Step 2: Convert to fraction form
   1,162.79/1,604.56 = 638.85/x
3. Step 3: Cross multiply
   1,162.79x = 1,604.56 × 638.85
4. Step 4: Simplify right side
   1,162.79x = 1,025,073.16
5. Step 5: Solve for x
   x = 1,025,073.16/1,162.79
6. Step 6: Final answer
   x = 881.56