Finding the Fourth Proportional to 13,386.39, 18,472.72 and 7,721.37

Step by Step Solution

1. Step 1: Write the proportion equation
   13,386.39 : 18,472.72 = 7,721.37 : x
2. Step 2: Convert to fraction form
   13,386.39/18,472.72 = 7,721.37/x
3. Step 3: Cross multiply
   13,386.39x = 18,472.72 × 7,721.37
4. Step 4: Simplify right side
   13,386.39x = 142,634,706.03
5. Step 5: Solve for x
   x = 142,634,706.03/13,386.39
6. Step 6: Final answer
   x = 10,655.20