Finding the Fourth Proportional to 2,105.42, 3,158.13 and 644.57

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.42 : 3,158.13 = 644.57 : x
2. Step 2: Convert to fraction form
   2,105.42/3,158.13 = 644.57/x
3. Step 3: Cross multiply
   2,105.42x = 3,158.13 × 644.57
4. Step 4: Simplify right side
   2,105.42x = 2,035,635.85
5. Step 5: Solve for x
   x = 2,035,635.85/2,105.42
6. Step 6: Final answer
   x = 966.86