Finding the Fourth Proportional to 2,619.72, 3,928.53 and 864.63

Step by Step Solution

1. Step 1: Write the proportion equation
   2,619.72 : 3,928.53 = 864.63 : x
2. Step 2: Convert to fraction form
   2,619.72/3,928.53 = 864.63/x
3. Step 3: Cross multiply
   2,619.72x = 3,928.53 × 864.63
4. Step 4: Simplify right side
   2,619.72x = 3,396,724.89
5. Step 5: Solve for x
   x = 3,396,724.89/2,619.72
6. Step 6: Final answer
   x = 1,296.60