Answer:
Total number of girls in the group =4
Total number of boys in the group =7
Probability of selecting atleast one boy and one girl =?
By considering following ways we can select
i) 1 girls +4 boys ⇒
4
C
1
×
7
C
4
ii) 2 girls +3 boys ⇒
4
C
2
×
7
C
3
iii) 3 girls +2 boys ⇒
4
C
3
×
7
C
2
iv) 4 girls +1 boy ⇒
4
C
4
×
7
C
1
Total number of ways =(
4
C
1
×
7
C
4
)+(
4
C
2
×
7
C
3
)+(
4
C
3
×
7
C
2
)+(
4
C
4
×
7
C
1
)
=140+210+84+7
=441
