Finding the Fourth Proportional to 1,172.38, 1,617.81 and 641.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,172.38 : 1,617.81 = 641.15 : x
2. Step 2: Convert to fraction form
   1,172.38/1,617.81 = 641.15/x
3. Step 3: Cross multiply
   1,172.38x = 1,617.81 × 641.15
4. Step 4: Simplify right side
   1,172.38x = 1,037,261.71
5. Step 5: Solve for x
   x = 1,037,261.71/1,172.38
6. Step 6: Final answer
   x = 884.75