Finding the Fourth Proportional to 13,690.05, 18,890.69 and 7,721.82

Step by Step Solution

1. Step 1: Write the proportion equation
   13,690.05 : 18,890.69 = 7,721.82 : x
2. Step 2: Convert to fraction form
   13,690.05/18,890.69 = 7,721.82/x
3. Step 3: Cross multiply
   13,690.05x = 18,890.69 × 7,721.82
4. Step 4: Simplify right side
   13,690.05x = 145,870,495.53
5. Step 5: Solve for x
   x = 145,870,495.53/13,690.05
6. Step 6: Final answer
   x = 10,655.22