Finding the Fourth Proportional to 2,591.90, 3,887.82 and 644.12

Step by Step Solution

1. Step 1: Write the proportion equation
   2,591.90 : 3,887.82 = 644.12 : x
2. Step 2: Convert to fraction form
   2,591.90/3,887.82 = 644.12/x
3. Step 3: Cross multiply
   2,591.90x = 3,887.82 × 644.12
4. Step 4: Simplify right side
   2,591.90x = 2,504,222.62
5. Step 5: Solve for x
   x = 2,504,222.62/2,591.90
6. Step 6: Final answer
   x = 966.17