Finding the Fourth Proportional to 1,136.76, 1,568.72 and 639.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,136.76 : 1,568.72 = 639.38 : x
2. Step 2: Convert to fraction form
   1,136.76/1,568.72 = 639.38/x
3. Step 3: Cross multiply
   1,136.76x = 1,568.72 × 639.38
4. Step 4: Simplify right side
   1,136.76x = 1,002,997.15
5. Step 5: Solve for x
   x = 1,002,997.15/1,136.76
6. Step 6: Final answer
   x = 882.33