Question

The average weight of a class of 40 student is 40 kg.If a new student whose weight is 40kg joins the class,then what is the new average weight of the class

Answer 1

Here average weight of 40 students = 40

We know that Average = Sum of all observations/ Total number of observations

∴ Sum of weight of 40 students ÷ 40 = 40 (average give is 40)

∴ Sum of weight of 40 students = 1600

Now one more student with weight 40 kg joins them

∴ Total number of students = 41

Sum of all 41 students = 1600 + 40

                                     = 1640

Now new average = sum of weight of 41 students ÷ 41

                               = 1640/41

                               = 40

∴ Average remains the same.