If some fresher engineering student has low GPA and not much extra?
I got into IIM Kozhikode with a 99.1 CAT percentile and 4.73 CGPA. Show them a good enough reason to pick you. I had decent extra curriculars, and work exp which helped me get through. Also, a lot of it was God's grace, so you should start praying too. IIM Calcutta will give everyone in the interview stage a fair chance of getting in. But, you need to show some spark, some extra-curriculars, some internships. Anything that makes you stand out from the rest of the crowd.