Finding the Fourth Proportional to 1,136.42, 1,568.18 and 639.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,136.42 : 1,568.18 = 639.05 : x
2. Step 2: Convert to fraction form
   1,136.42/1,568.18 = 639.05/x
3. Step 3: Cross multiply
   1,136.42x = 1,568.18 × 639.05
4. Step 4: Simplify right side
   1,136.42x = 1,002,150.95
5. Step 5: Solve for x
   x = 1,002,150.95/1,136.42
6. Step 6: Final answer
   x = 881.85