MAT Exam 2020 Paper

Concept:The total number of students in each class returns to its original value after all the transfers.Explanation:Let each class originally have $100$ students.After the transfers, the number of students in class $X$ is:$X = 100 + 5 - 5 = 100$For class $Y$:$Y = 100 + 5 - 5 + 5 - 5 = 100$For class $Z$:$Z = 100 - 5 + 5 = 100$Thus, every class again has $100$ students.The transfers into and out of class $X$ cancel each other completely.Similarly, the transfers into and out of class $Y$ cancel each other completely.So the maximum possible average of class $Y$ is same as the maximum possible average of class $X$.Hence, Quantity A is equal to Quantity B.Answer:Option (c): If Quantities A and B are equal.