Answer:
Step-by-step explanation:
We need to choose 4 swimmers from 6boys and 7 girls.
Total swimmers, both boys and girls are (6 + 7) = 13.
From 13 swimmers 4 swimmers can be chosen in 13C4 = [tex]\frac{13!}{4! times 9!}[/tex] = [tex]55times13[/tex] ways.
It is also given that we should choose 3 boys for the relay team from total 6 boys. From total of 6 boys, 3 boys can be chosen in 6C3 = [tex]\frac{6!}{3!times3!}[/tex] = 20 ways.
From 7 girls, 1 girl can be chosen in 7C1 = 7 ways.
Hence, the required probability is [tex]\frac{7times20}{55times13}[/tex] = [tex]\frac{7times4}{11times13} = \frac{28}{143}[/tex]
