Probability question

[q_fruit]

confused about this question..

Approximately 4% of Canadians have type AB blood. Suppose 70%of Canadians are urban dwellers. What is the probability that a Canadian selected at random

a) has type AB blood and also lives in the city?

b) does not have AB blood and lives in the country?

c) In a group of four randomly selected Canadians, what is the estimated probability that at least three of them have type AB blood?

 

[Gene]

They are independent so the probabilities are multiplied.
a) .04*.70 = 2.8%
b) .96*.30 = 28.8%
c) There is 1 way of choosing 4 people from 4 and the probability of all 4 having AB is .04^4
There are 4 ways of choosing 3 people from 4 and the probability of 3 having AB and 1 not, is .04^3*.96
The sum of those is
1*.04^4 + 4*.04^3*.96 = .025%