Finding the Fourth Proportional to 1,172.71, 1,618.33 and 641.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,172.71 : 1,618.33 = 641.59 : x
2. Step 2: Convert to fraction form
   1,172.71/1,618.33 = 641.59/x
3. Step 3: Cross multiply
   1,172.71x = 1,618.33 × 641.59
4. Step 4: Simplify right side
   1,172.71x = 1,038,304.34
5. Step 5: Solve for x
   x = 1,038,304.34/1,172.71
6. Step 6: Final answer
   x = 885.39