The music class consists of 4 girls and 8 boys. How many ways can a group of 3 be formed if it has to include at least one boy?	Select:
A) 155
B) 158
C) 161
D) 165
E) 216
Reverse combinatorics approach is preferred method on this one   Note that at least 1 boy gives clue to using this method   All combinations - four girls = answer   All combinations is 12C3 = 220   All girls 4C3 = 4   So our answer is   220-4= 
<gadget id="calculator">  220-4</gadget>
<output>216</output>
216   Hence, answer is (216)
<result>E</result>
The music class consists of 4 girls and 8 boys. How many ways can a group of 3 be formed if it has to include at least one boy?