Finding the Fourth Proportional to 13,109, 18,090.42 and 7,521.80

Step by Step Solution

1. Step 1: Write the proportion equation
   13,109 : 18,090.42 = 7,521.80 : x
2. Step 2: Convert to fraction form
   13,109/18,090.42 = 7,521.80/x
3. Step 3: Cross multiply
   13,109x = 18,090.42 × 7,521.80
4. Step 4: Simplify right side
   13,109x = 136,072,521.16
5. Step 5: Solve for x
   x = 136,072,521.16/13,109
6. Step 6: Final answer
   x = 10,380.08