Finding the Fourth Proportional to 13,608.72, 18,779.01 and 7,639.25

Step by Step Solution

1. Step 1: Write the proportion equation
   13,608.72 : 18,779.01 = 7,639.25 : x
2. Step 2: Convert to fraction form
   13,608.72/18,779.01 = 7,639.25/x
3. Step 3: Cross multiply
   13,608.72x = 18,779.01 × 7,639.25
4. Step 4: Simplify right side
   13,608.72x = 143,457,458.25
5. Step 5: Solve for x
   x = 143,457,458.25/13,608.72
6. Step 6: Final answer
   x = 10,541.58