Finding the Fourth Proportional to 2,615.78, 3,923.89 and 667.98

Step by Step Solution

1. Step 1: Write the proportion equation
   2,615.78 : 3,923.89 = 667.98 : x
2. Step 2: Convert to fraction form
   2,615.78/3,923.89 = 667.98/x
3. Step 3: Cross multiply
   2,615.78x = 3,923.89 × 667.98
4. Step 4: Simplify right side
   2,615.78x = 2,621,078.37
5. Step 5: Solve for x
   x = 2,621,078.37/2,615.78
6. Step 6: Final answer
   x = 1,002.02