(a) To divide 9 people into a group of 6 and a group of 3, we calculate the number of combinations of choosing 6 people out of 9. This is given by:

\(\binom{9}{6} = \binom{9}{3} = 84\)

Thus, there are 84 ways to divide the 9 people into a group of 6 and a group of 3.

(b) To find the probability that a group of 5 people contains all 3 of the Baker children, we first calculate the number of ways to choose 3 Baker children and 2 others from the remaining 6 people (4 Ahmeds and 2 Bakers):

Number of ways to choose 2 from 6: \(\binom{6}{2} = 15\)

Total number of ways to choose any 5 people from 9: \(\binom{9}{5} = 126\)

The probability is then:

\(\frac{15}{126} = \frac{5}{42}\)