Finding the Fourth Proportional to 1,335.25, 2,003.31 and 641.98

Step by Step Solution

1. Step 1: Write the proportion equation
   1,335.25 : 2,003.31 = 641.98 : x
2. Step 2: Convert to fraction form
   1,335.25/2,003.31 = 641.98/x
3. Step 3: Cross multiply
   1,335.25x = 2,003.31 × 641.98
4. Step 4: Simplify right side
   1,335.25x = 1,286,076.54
5. Step 5: Solve for x
   x = 1,286,076.54/1,335.25
6. Step 6: Final answer
   x = 963.17