Can someone help please ?

For which of the following counts would a binomial probability model not be reasonable? a)the number of people in a classroom born in januaryb) the number of people in a classroom with red hair c) the number of people admitted to a hospital in a day with a particular disease d) the number of heart beats in a one-minute perio.

According to the general equation for conditional probability if p(anb)=3/7 and p(b)=7/8 what is p(a i b)

You buy a veido game for $60 and the sales tax is 8% what is the total cost for the game including the sales tax