Finding the Fourth Proportional to 21,136.48, 29,168.78 and 13,071.31

Step by Step Solution

1. Step 1: Write the proportion equation
   21,136.48 : 29,168.78 = 13,071.31 : x
2. Step 2: Convert to fraction form
   21,136.48/29,168.78 = 13,071.31/x
3. Step 3: Cross multiply
   21,136.48x = 29,168.78 × 13,071.31
4. Step 4: Simplify right side
   21,136.48x = 381,274,027.42
5. Step 5: Solve for x
   x = 381,274,027.42/21,136.48
6. Step 6: Final answer
   x = 18,038.67