Finding the Fourth Proportional to 1,139.03, 1,571.83 and 641.66

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.03 : 1,571.83 = 641.66 : x
2. Step 2: Convert to fraction form
   1,139.03/1,571.83 = 641.66/x
3. Step 3: Cross multiply
   1,139.03x = 1,571.83 × 641.66
4. Step 4: Simplify right side
   1,139.03x = 1,008,586.37
5. Step 5: Solve for x
   x = 1,008,586.37/1,139.03
6. Step 6: Final answer
   x = 885.47