Finding the Fourth Proportional to 13,308.72, 18,365.40 and 7,639.50

Step by Step Solution

1. Step 1: Write the proportion equation
   13,308.72 : 18,365.40 = 7,639.50 : x
2. Step 2: Convert to fraction form
   13,308.72/18,365.40 = 7,639.50/x
3. Step 3: Cross multiply
   13,308.72x = 18,365.40 × 7,639.50
4. Step 4: Simplify right side
   13,308.72x = 140,302,473.30
5. Step 5: Solve for x
   x = 140,302,473.30/13,308.72
6. Step 6: Final answer
   x = 10,542.15