A selection of soft-drink users is asked to taste the two disguised soft drinks and indicate which they prefer. The accompanying data contains the results of a simulated challenge on a college campus.

AgePreference:

17Brand B

20Brand A

22Brand B

18Brand A

18Brand B

24Brand B

23Brand B

19Brand B

22Brand B

19Brand A

18Brand B

17Brand B

21Brand B

23Brand B

20Brand B

20Brand B

24Brand A

16Brand B

19Brand B

21Brand A

18Brand B

20Brand A

19Brand B

19Brand B

22Brand B

17Brand B

21Brand B

21Brand B

20Brand B

22Brand A

19Brand A

23Brand A

22Brand A

18Brand B

19Brand A

22Brand B

20Brand A

24Brand A

22Brand A

18Brand B

19Brand B

18Brand B

17Brand B

23Brand B

18Brand A

20Brand B

24Brand A

20Brand A

24Brand A

18Brand A

19Brand A

22Brand B

18Brand B

22Brand B

24Brand B

16Brand A

23Brand A

19Brand A

22Brand A

22Brand A

20Brand B

22Brand A

18Brand B

24Brand B

22Brand A

22Brand B

19Brand B

20Brand B

19Brand A

23Brand A

20Brand B

21Brand A

19Brand A

23Brand B

24Brand B

19Brand A

21Brand B

18Brand A

19Brand B

22Brand A

16Brand B

21Brand B

21Brand A

16Brand A

21Brand A

21Brand B

19Brand B

23Brand A

16Brand A

18Brand B

21Brand A

19Brand A

21Brand B

23Brand A

19Brand A

19Brand B

22Brand A

20Brand A

23Brand A

a. Of those students who are less than 19 years old, calculate the probability that a randomly chosen student prefers Brand A < 19 and Brand B< 19.

b. Of those students who are at least 19 years old, calculate the probability that a randomly chosen student prefers (1) Brand A > or equal 19 and (2) Brand B > or equal 19.