Average - General Questions

The average weight of 11 persons increases by 2.5 kg when a new person replaces one of them weighing 64 kg. What is the weight of the new person?

The average of 9 numbers is 37. When one more number is added, the average becomes 42. What is the new number?

The average of 5 numbers is 55. When one more number is added, the average becomes 56. What is the new number?

A batsman has a certain average after 8 innings. In the 9th innings he scores 55 runs and thereby increases his average by 2. What is his average after the 9th innings?

The average marks of a class of 43 students is 51 and that of another class of 27 students is 56. What is the average of all the students together?