Yes, you're right.
If we denote the birth of a girl as a succes, that is we let X denote the number of girls,...then where . (In this case the formula is ofcourse the same for the number of boys)
A family has 4 children. Assuming that boys and girls are equally likely, calculate the probability, using fractions, and Bernoulli's formula (please use this specific formula when necessary)
(i) there are exactly 2 boys.
(ii) there are exactly 3 girls.
(iii) there is at least one boy.
As far as I know, 'k' means the number of successes, 'n' is the number of Bernoulli trials, while P is the probability, hope i am right.
Any input will do >_< Thanks...