Finding the Fourth Proportional to 2,621.72, 3,931.52 and 866.64

Step by Step Solution

1. Step 1: Write the proportion equation
   2,621.72 : 3,931.52 = 866.64 : x
2. Step 2: Convert to fraction form
   2,621.72/3,931.52 = 866.64/x
3. Step 3: Cross multiply
   2,621.72x = 3,931.52 × 866.64
4. Step 4: Simplify right side
   2,621.72x = 3,407,212.49
5. Step 5: Solve for x
   x = 3,407,212.49/2,621.72
6. Step 6: Final answer
   x = 1,299.61