 Hello and welcome to the session. In this session we will discuss the question which says that find fourth term from the last term towards the first term of the AB, 4, 9, 14 and so on up to 254 and the options are option A, 19, option B, 24, option C, 269 and option D, Now, before starting the solution of this question, we should know what is out and that is the last term of an AP with m terms there, what is the first term and D is the common difference is A is equal to A plus m minus 1 the whole into D. Now, this result will work out as a key idea for solving out this question and now we will start with the solution. So, here the AP is given to us so given the AP, 4, 9, 14 and so on up to 254 is equal to 4 and the common difference D is equal to 9 minus 4 which is equal to 5. Also the last term and this AP that is this term so the last term is 254. So, using this formula which is given in the key idea, now m minus 1 the whole into D so put in the handings of A, D and m here this implies 254 is equal to 4 plus m minus 1 the whole into 5 which further implies 254 minus 4 is equal to n minus 1 the whole into 5 which implies 250 is equal to n minus 1 the whole into 5 which further implies on dividing both sides by 5 it will be 50 is equal to n minus 1. Now, this implies 2 plus 1 is equal to n and this implies n is equal to 51. Therefore, the number of terms in the given AP is equal to 51. Now, since there are 51 terms in the given AP so we have fourth term, 48th term that is A48 is equal to A plus whole into D is equal to now here we will put the value of A and D this 4 and 5 respectively. So, this will be 4 plus 48 minus 1 is 47 into 5 which is further equal to 4 plus 235 239. Therefore, and that's all for the session hope you all have enjoyed the session.