Finding the Fourth Proportional to 13,608.72, 18,778.42 and 7,639.08

Step by Step Solution

1. Step 1: Write the proportion equation
   13,608.72 : 18,778.42 = 7,639.08 : x
2. Step 2: Convert to fraction form
   13,608.72/18,778.42 = 7,639.08/x
3. Step 3: Cross multiply
   13,608.72x = 18,778.42 × 7,639.08
4. Step 4: Simplify right side
   13,608.72x = 143,449,852.65
5. Step 5: Solve for x
   x = 143,449,852.65/13,608.72
6. Step 6: Final answer
   x = 10,541.02