Finding the Fourth Proportional to 1,136.71, 1,568.62 and 639.33

Step by Step Solution

1. Step 1: Write the proportion equation
   1,136.71 : 1,568.62 = 639.33 : x
2. Step 2: Convert to fraction form
   1,136.71/1,568.62 = 639.33/x
3. Step 3: Cross multiply
   1,136.71x = 1,568.62 × 639.33
4. Step 4: Simplify right side
   1,136.71x = 1,002,865.82
5. Step 5: Solve for x
   x = 1,002,865.82/1,136.71
6. Step 6: Final answer
   x = 882.25