A class of twelve children has two more boys than girls

Q. A class of twelve children has two more boys than girls. A group of three children are randomly picked from this class to accompany the teacher on a field trip. What is the probability that the group accompanying the teacher contains more girls than boys?

Ans: Option B

Sol:

∵B=G+2 and B+G=12 ⇒ B=7, G=5
Total ways of picking 3 children = 12C3

Favourable ways (when No. of girls are > No. of Boys)

= Either (2G and 1B) or (3G)

=( 5C2 × 7C1)+ 5C3=10×7+10=80

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