The number of ants in his farm after 12 weeks is 218.
Step-by-step explanation:
Step 1:
It is given that there are 15 ants initially and the ant population increases by 25% each week.
This is an exponential rate of increase that can be modeled by the following equation:
Number of ants after n weeks = Initial number of ants * 
Step 2:
Rate of increase = 25% = 25 / 100 = 0.25
Number of weeks = 12
Number of ants after 12 weeks = 15*
= 218.27 (rounded off to 218)
Step 3:
Answer:
The number of ants in his farm after 12 weeks is 218.