This book has been written as per syllabus of WBUT, and other universities and is suitable for the students of BBA and MBA branch. In writing this I got inspiration from Sanjoy kumar of NPTI, Joydeb Ganguly, Principal of DISTM, Shuva Bhattacherjee, Coarse Coordination of AIMS Syndicate. On the other hand, some teachers like Nabanita Naha (DISTM) , Somnath Ghosal (AIMS Syndicate) also inspired me to write this book. I am grateful to my student cum colleague Sri Sandip Banerjee for helping to computerize the whole book.