Finding the Fourth Proportional to 2,105.20, 3,158.37 and 644.35

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.20 : 3,158.37 = 644.35 : x
2. Step 2: Convert to fraction form
   2,105.20/3,158.37 = 644.35/x
3. Step 3: Cross multiply
   2,105.20x = 3,158.37 × 644.35
4. Step 4: Simplify right side
   2,105.20x = 2,035,095.71
5. Step 5: Solve for x
   x = 2,035,095.71/2,105.20
6. Step 6: Final answer
   x = 966.70