Finding the Fourth Proportional to 2,105.54, 3,158.30 and 644.70

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.54 : 3,158.30 = 644.70 : x
2. Step 2: Convert to fraction form
   2,105.54/3,158.30 = 644.70/x
3. Step 3: Cross multiply
   2,105.54x = 3,158.30 × 644.70
4. Step 4: Simplify right side
   2,105.54x = 2,036,156.01
5. Step 5: Solve for x
   x = 2,036,156.01/2,105.54
6. Step 6: Final answer
   x = 967.05