Finding the Fourth Proportional to 2,105.48, 3,158.40 and 644.76

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.48 : 3,158.40 = 644.76 : x
2. Step 2: Convert to fraction form
   2,105.48/3,158.40 = 644.76/x
3. Step 3: Cross multiply
   2,105.48x = 3,158.40 × 644.76
4. Step 4: Simplify right side
   2,105.48x = 2,036,409.98
5. Step 5: Solve for x
   x = 2,036,409.98/2,105.48
6. Step 6: Final answer
   x = 967.20