Finding the Fourth Proportional to 2,487.72, 3,731.33 and 638.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,487.72 : 3,731.33 = 638.78 : x
2. Step 2: Convert to fraction form
   2,487.72/3,731.33 = 638.78/x
3. Step 3: Cross multiply
   2,487.72x = 3,731.33 × 638.78
4. Step 4: Simplify right side
   2,487.72x = 2,383,498.98
5. Step 5: Solve for x
   x = 2,383,498.98/2,487.72
6. Step 6: Final answer
   x = 958.11