Finding the Fourth Proportional to 1,139.00, 1,571.81 and 641.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.00 : 1,571.81 = 641.59 : x
2. Step 2: Convert to fraction form
   1,139.00/1,571.81 = 641.59/x
3. Step 3: Cross multiply
   1,139.00x = 1,571.81 × 641.59
4. Step 4: Simplify right side
   1,139.00x = 1,008,450.44
5. Step 5: Solve for x
   x = 1,008,450.44/1,139.00
6. Step 6: Final answer
   x = 885.39