As known that for admission into IIM's IPM one has to go through A.T and a personal interview.
The Aptitude test consists of 2 parts. One that of quantitative aptitude and other being the verbal ability. For quantitative aptitute one can refer to the book Qbjective Arithmetic of R.S. Aggarwal, though this book is meant for the entrances of railway and other similar things but since the syllabus is quite the same so this book is helpful as well. Apart from this one has to completely solve NCERT Maths book for class XI and XII. As chapters like P&C, Binomial Theorem, Complex Number, Functions and Calculus are also included for the test.
For the verbal ability thing any good English book like that of Wren n Martin, Nesfield, R.S Aggarwal's verbal ability is good.
The Pearson guide is a good book as well which combines the Objective Arithmetic and Verbal ability in one but I think that one has to completely solve class XI and XII NCERT of Maths as well.
For the interview thing one has to be aware of all the General Knowledge thing. Reading newspaper , magazines is always helpful. One has to look upon his body language as well. Co curricular activities are always helpful.