[collegegirl08]

Hello- I was wondering if someone could help me out? I was wondering if I am correct on these questions?

(a) A sales person finds that in the long run one out of five sales calls are successful in the market he operates. Thirty sales calls are made every week. Let X denote the number of successful calls in a week. Is X a binomial random variable? Explain.

(b) A new treatment for baldness is known to be effective in 70% of the cases treated. Four bald members of the same family are treated. Let X denote the number of successfully treated members of the family. Is X a binomial random variable? Explain.

I said that both of these examples are random variables. I said it was because there was a fixed number, there are only 2 outcomes for each trial (success or failure), there is a constant probability of success, and the trials are independent of each other.

[morgaine300]

Four members of the same family. Do you think that would be independent? Or random?

[collegegirl08]

Four members of the same family are not independent. Is that correct? So for (b), x is not a binomial random variable.

[morgaine300]

They're not independent at all. Baldness is a genetic trait. I would also have to assume that how well some treatment works would be the same. That's also not random.