Finding the Fourth Proportional to 1,290.57, 1,936.59 and 641.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,290.57 : 1,936.59 = 641.31 : x
2. Step 2: Convert to fraction form
   1,290.57/1,936.59 = 641.31/x
3. Step 3: Cross multiply
   1,290.57x = 1,936.59 × 641.31
4. Step 4: Simplify right side
   1,290.57x = 1,241,954.53
5. Step 5: Solve for x
   x = 1,241,954.53/1,290.57
6. Step 6: Final answer
   x = 962.33