A uiniversity is considering a ban on smartphones in all classrooms. A published

Question

A uiniversity is considering a ban on smartphones in all classrooms. A published poll states that 20% of students support the ban, while 70% of students are against it and 10% have no opinion. You decide to conduct an exit poll on the voting day and talk to 30 students about the ban.

1) What is the probability that at least 8 students in your exit poll support the ban? Justify your answer by showing work.

2) How many students in your exit poll group do you expect to support the ban? Show work.

3) In your exit poll group, you find that 15 students support the ban. Given your observations, do you believe the poll? Explain your answer (numerical justifications please).

Explanation / Answer

1) Given n = 30 and p = 0.20

P(x 8) = 1 - P(x 7) = 1 - binomcdf(30,0.20,7) = 0.2392

2) E(X) = = np = 30(0.20) = 6

3) P(x 15) = 1 - P(x 14) = 1 - binomcdf(30,0.20,14) = 0.0002312256

Probability of getting 15 or more students support the ban is less than 0.05, this suggests that if 20% of students support the ban, then in the sample of 30, its highly unusual to get 15 students support the ban. We can conclude that more than 20% of students support the ban.

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