 Hello and welcome to the session. In this session we will discuss a question which says that a quantity is tops twice, what is the probability of getting at least one tail? Now before starting the solution of this question we should know a result and that is the probability of an event e that is p e is equal to number of outcomes favorable to e whole upon total number of possible outcomes. Now this result will work out as a key idea for solving out this question and now we will start with the solution. Now it is given that a coin is tossed twice. Now even experiment of tossing a coin twice the total number to the outcomes that is head-head, head-tail, tail-head and tail-tail. Now we have to find the probability of getting at least one tail. Now let of getting at least one tail. So number of outcomes favorable to e that is getting at least one tail. So here the number of outcomes favorable to e are that is tail-head and tail-tail where in all these three we are getting at least one tail. Now for finding out the probability we will use the formula which is given in the key idea. So probability of the event e that is probability of getting at least one tail is equal to number of outcomes favorable to e over total number of possible outcomes. So here the total number of possible outcomes are 4 and number of outcomes favorable to e are. So putting these values here this will be equal to 3 by 4. Therefore probability of getting at least one tail is equal to 3 by 4. So this is the solution of the given question and that's all for this session. Hope you all have enjoyed the session.