The Average Weight of Students in a Class is 43 kg :

The average weight of students in a class is 43 kg. Four new students are admitted to the class whose weights are 42 kg, 36.5 kg and 42.5 kg respectively. Now the average weight of the students of the class is 42.5 kg. The number of students in the beginning was

1. 10
2. 15
3. 20
4. 25