Let there be z pupils in the class
Total increase in marks = ( z x 1/2) = z/2
=> z/2 = (83-63) => z/2 = 20
=> z = 40
In Arun's opinion, his weight is greater than 65 kg but less than 72 kg. His brother doest not agree with Arun and he thinks that Arun's weight is greater than 60 kg but less than 70 kg. His mother's view is that his weight cannot be greater than 68 kg. If all are them are correct in their estimation, what is the average of different probable weights of Arun?