Finding the Fourth Proportional to 1,287.02, 1,931.88 and 638.24

Step by Step Solution

1. Step 1: Write the proportion equation
   1,287.02 : 1,931.88 = 638.24 : x
2. Step 2: Convert to fraction form
   1,287.02/1,931.88 = 638.24/x
3. Step 3: Cross multiply
   1,287.02x = 1,931.88 × 638.24
4. Step 4: Simplify right side
   1,287.02x = 1,233,003.09
5. Step 5: Solve for x
   x = 1,233,003.09/1,287.02
6. Step 6: Final answer
   x = 958.03