Finding the Fourth Proportional to 1,136.31, 1,568.27 and 638.99

Step by Step Solution

1. Step 1: Write the proportion equation
   1,136.31 : 1,568.27 = 638.99 : x
2. Step 2: Convert to fraction form
   1,136.31/1,568.27 = 638.99/x
3. Step 3: Cross multiply
   1,136.31x = 1,568.27 × 638.99
4. Step 4: Simplify right side
   1,136.31x = 1,002,097.81
5. Step 5: Solve for x
   x = 1,002,097.81/1,136.31
6. Step 6: Final answer
   x = 881.89