The average weight of 29 students is 28 kg. By the admission of a new student, the average weight is reduced to 27.2 kg. The weight of the new student is  Select the correct option
A) 4 kg  B) 21.6 kg  C) 22.4 kg  D) 21 kg  E) none of these

Rationale: "exp . the total weight of 29 students = 29 * 28 the total weight of 30 students = 30 * 27.2 weight of the new student = ( 30 * 27.2 – 29 * 28 ) = 816 - 812 = 4 answer : a"
Answer: A