ISI 2015 PEB QUESTION 3

[saumya singha]

Please someone who has solved question 3 ,can you explain me how do we solve it?
how do we incorporate the population in the answer?
i could do till the point where a person would chose to buy from beyond the border when p(1+t)>p+2kd.
how do we solve further?
please do share your splution

[Akshay Jain]

I am not sure about my solution but with this u can get an idea how to incorporate population into ur solution...