The average weight of students in a class is 49kg. Five new students are admitted in the class whose weights are 45 kg, 46.8 kg, 47.4 kg, 54.2 kg and 63.6 kg. Now, the average weight of all the students in the class is 50 kg. The number of students in the class in the beginning was:
1
10
2
12
3
8
4
7