Finding the Fourth Proportional to 2,105.74, 3,158.50 and 644.79

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.74 : 3,158.50 = 644.79 : x
2. Step 2: Convert to fraction form
   2,105.74/3,158.50 = 644.79/x
3. Step 3: Cross multiply
   2,105.74x = 3,158.50 × 644.79
4. Step 4: Simplify right side
   2,105.74x = 2,036,569.22
5. Step 5: Solve for x
   x = 2,036,569.22/2,105.74
6. Step 6: Final answer
   x = 967.15