 Hello and welcome to the session. Let us understand the following question which says, In a school, students thought of planting trees in and around the school to reduce air pollution. It was decided that the number of trees that each section of each class will plant will be the same as the class in which they are studying. For example, a section of class 1 will plant one tree, a section of class 2 will plant two trees and so on till class 12. There are three sections of each class. How many trees will be planted by the students? Now let's proceed on to the solution. Since each section of each class plants the same number of trees as the class number and it is also given that there are three sections of each class. So total number of trees planted by each class is 1 plus 2 plus 3 plus 4 so on till 12. Now since there are three sections, so in order to find the total number of trees planted by the students, we will multiply this sum by 3. Now we have our AP as 1, 2, 3, 4 so on till 12. Here we can see A first term is equal to 1, D common difference is equal to 1 and N the Nth term is equal to 12. So let us find the sum that is Sn is equal to N by 2 multiplied by 2A plus N minus 1D which is equal to N is equal to 12 by 2 multiplied by 2 multiplied by 1 plus 12 minus 1 multiplied by 1 which is equal to 12 gets cancelled by 2 and we get 6 multiplied by 2 plus 11 which is equal to 6 multiplied by 13 which is equal to 78. Now total number of trees planted is equal to 3 multiplied by 78 because there are three sections of each class which is equal to 234. Hence total number of trees is equal to 234 which is our required answer. I hope you understood this question. That's all for the session. Bye and have a nice day.