Finding the Fourth Proportional to 1,138.82, 1,571.72 and 641.48

Step by Step Solution

1. Step 1: Write the proportion equation
   1,138.82 : 1,571.72 = 641.48 : x
2. Step 2: Convert to fraction form
   1,138.82/1,571.72 = 641.48/x
3. Step 3: Cross multiply
   1,138.82x = 1,571.72 × 641.48
4. Step 4: Simplify right side
   1,138.82x = 1,008,227.67
5. Step 5: Solve for x
   x = 1,008,227.67/1,138.82
6. Step 6: Final answer
   x = 885.32