The average weight of 20 girls increases by 2 kg when a new girl comes in place of one of them weighing 40 kg. What might be the weight of the new girl?  Pick one:
A) 85 kg
B) 90 kg
C) 80 kg
D) 75 kg
E) 70 kg

Rationale: "total weight increased = 20 x 2 kg = 40 kg . weight of new person = 40 + 40 kg = 80 kg answer : c"
Answer: C