I'm from chennai. Here, Only an apartment that is worth Rs 50,00,000 & above can fetch you Rs 12,000 as rent in todays scenario i.e. when u buy an apartment today for 50 lakhs, you can only rent it to a max of 12 thousand. So if this is the case in chennai, the cost of purchasing an apartment in mumbai & delhi should be even more & im quite sure the rent should only be a little more.
So, i suppose the data taken for comparison is wrong in this article. Probably a 25 lakhs apartment can only fetch you 8000 in rent in chennai. And should be almost the same in other metropolitan cities. So, i dont know where the author of this article hail from.