At a university, 15% of students smoke. a) Calculate the expected number of smok

Question

At a university, 15% of students smoke. a) Calculate the expected number of smokers in a random sample of 150 students from this university (please do not round your answer): b) The university gym opens at 9 am on Saturday mornings. One Saturday morning at 8: 55 am there are 22 students outside the gym waiting for it to open. Should you use the same approach from part (a) to calculate the expected number of smokers among these 22 students? No, it is unlikely that smoking habits and waking up early to go to the gym on Saturday are independent. Yes, it is reasonable to believe that people who go to the gym when it first opens on Saturday mornings is a representative sample.

Explanation / Answer

Given:

P=15%=0.15, n = 150

a)

E(x) = np = 150*0.15 = 22.5

b) No, these 22 students are not a random sample from the university's example, it might be argued that the proportion of smokers amoung gym at 9am on a saturday morning would be lower than the proportion of university as a whole

a) No, it is unlikely that smoking habits and waking up early to go to the gym on saturday are independent.

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