Finding the Fourth Proportional to 23,172.80, 31,978.72 and 13,613.09

Step by Step Solution

1. Step 1: Write the proportion equation
   23,172.80 : 31,978.72 = 13,613.09 : x
2. Step 2: Convert to fraction form
   23,172.80/31,978.72 = 13,613.09/x
3. Step 3: Cross multiply
   23,172.80x = 31,978.72 × 13,613.09
4. Step 4: Simplify right side
   23,172.80x = 435,329,376.49
5. Step 5: Solve for x
   x = 435,329,376.49/23,172.80
6. Step 6: Final answer
   x = 18,786.22