Finding the Fourth Proportional to 1,139.10, 1,571.88 and 641.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.10 : 1,571.88 = 641.82 : x
2. Step 2: Convert to fraction form
   1,139.10/1,571.88 = 641.82/x
3. Step 3: Cross multiply
   1,139.10x = 1,571.88 × 641.82
4. Step 4: Simplify right side
   1,139.10x = 1,008,864.02
5. Step 5: Solve for x
   x = 1,008,864.02/1,139.10
6. Step 6: Final answer
   x = 885.67