Finding the Fourth Proportional to 1,138.83, 1,571.40 and 641.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,138.83 : 1,571.40 = 641.37 : x
2. Step 2: Convert to fraction form
   1,138.83/1,571.40 = 641.37/x
3. Step 3: Cross multiply
   1,138.83x = 1,571.40 × 641.37
4. Step 4: Simplify right side
   1,138.83x = 1,007,845.87
5. Step 5: Solve for x
   x = 1,007,845.87/1,138.83
6. Step 6: Final answer
   x = 884.99