All solutions here are SUGGESTED. Mr. Teng will hold no liability for any errors. Comments are entirely personal opinions.
Firstly, the probability of picking a free gift is constant. Secondly, there is only two possible outcomes, i.e., the packets either contain a free gift or do no contain a free gift.
Since is large, approximately.
This is a simple question on binomial distribution and approximation. Students had to be cautious to answer (i) in context.