The enegineer ROUGHED OUT his ideas on a piec of paper while he talked.

A pen of mass 'm' is lying on a piece of paper of mass M placed on a rough table. If the coefficient of friction between the pen and paper, and, the paper and table are mu_(1) and mu_(2) , respectively, then the minimum horizontal force with which the paper has to be pulled for the pen to start slipping is given by-

In the intermediate examination a candidate has to pass in each of his 6 papers . The number of ways in within he can fail is

A square piece of paper is folded in a particular manner and punched and then unfolded. The unfolded paper is given below. Find out the manner in which the paper was folded and punched from the answer figure.