I have this question which I'm finding hard to solve:
Each of a large number of researchers, in different parts of the country, carries out a survey in which they question randomly chosen people in turn, until they find one who admits to smoking more than 20 cigarettes a day. As soon as each researcher hasn't found one such person, the total number of people is noted. In collating the results of the survey, it is found that on average 95% of the researchers had to ask at least 30 people. Use this figure to estimate the probability that one person at random would admit more than 20 cigarettes a day.
What I think I have to do:
95/100 is the probability of success, 30 is the number of trials. I should do 95/100^30*5/100, to get the probability which is just the probability for one trial.
I don't get the right answer. The right answer is 0.0018.
Thanks in advance...