Answer:
(a) 0.4242
(b) 0.0707
Step-by-step explanation:
The total number of ways of selecting 8 herbs from 12 is
(a) If 2 herbs are selected, then there are 8 - 2 = 6 herbs to be selected from 12 - 8 = 10. The number of ways of the selection is then
Note that this is the number of ways that both are included. We would have multiplied by 2! if any of them were to be included.
The probability =
(b) If 5 herbs are selected, then there are 8 - 5 = 3 herbs to be selected from 12 - 5 = 7. The number of ways of the selection is then
This is the number of ways that both are included. We would have multiplied by 5! if any of them were to be included. In that case, our probability will exceed 1; this implies that certainly, at least, one of them is included.
The probability =