There are 2 sections A and B in a class, consisting of 60 and 70 students respectively. If the average weight of section A is 60kg and that of section B is 80kg, Find the average of the whole class?
Choose the correct option:
A) 50.78 kg B) 49.32 kg C) 70.76 kg D) 69.15 kg E) 70.89 kg

Rationale: "total weight of 60 + 70 students = 60 * 60 + 70 * 80 = 3600 + 5600 average weight of the class is = 9200 / 130 = 70.76 kg answer is c"
Answer: C