CBSE Class 10 Answered

Since the class till which the school runs is not mentioned we will assume that it is till 12th

We will First find the number of trees planted by one section of each class.

 Then multiply this by 3  there are three sections in each class.

First class I section will plant 1 tree

Second class I section will plant 2 trees and so on 12 th class 1 section will plant 12 trees

The number of trees planted by a section of each class forms an arithmetic progression.

The first term of the arithmetic progression is, a = 1 and the common difference is also 1.

The number of terms in the arithmetic progression is equal to the number of classes, i.e., 12

 And the sum of an arithmetic progression can be determined by using the formula.