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 = 
83 + 58 = 141
55 + 68 = 123
92 + 69 = 161
48 + 72 = 120
69 + 77 = 146
95 + 88 = 183
78 + 43 = 121
86 + 77 = 163
79 + 47 = 126
74 + 59 = 133
85 + 94 = 179
69 + 78 = 147
91 + 89 = 180
48 + 95 = 143
66 + 45 = 111
73 + 86 = 159
98 + 74 = 172
23 + 79 = 102
163 - 125 = 38
243 - 74 = 169
208 - 92 = 116
262 - 77 = 185
122 - 86 = 36
197 - 82 = 115
159 - 41 = 118
299 - 151 = 148
181 - 87 = 94
196 - 159 = 37
232 - 168 = 64
165 - 76 = 89
241 - 85 = 156
149 - 38 = 111
184 - 95 = 89
124 - 67 = 57
142 - 96 = 46
272 - 119 = 153
261 - 95 = 166
225 - 88 = 137
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