Finding the Fourth Proportional to 1,138.69, 1,571.33 and 641.32

Step by Step Solution

1. Step 1: Write the proportion equation
   1,138.69 : 1,571.33 = 641.32 : x
2. Step 2: Convert to fraction form
   1,138.69/1,571.33 = 641.32/x
3. Step 3: Cross multiply
   1,138.69x = 1,571.33 × 641.32
4. Step 4: Simplify right side
   1,138.69x = 1,007,717.50
5. Step 5: Solve for x
   x = 1,007,717.50/1,138.69
6. Step 6: Final answer
   x = 884.98