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The proportion of students who own a cell phone on college campuses across the c

ID: 3295873 • Letter: T

Question

The proportion of students who own a cell phone on college campuses across the country has increased tremendously over the past few years. It is estimated that approximately 90% of students now own a cell phone. Fifteen students are to be selected at random from a large university. Assume that the proportion of students who own a cell phone at this university is the same as nationwide. Let X = the number of students in the sample of 15 who own a cell phone.

The probability distribution of random variable, X, is defined as follows:

11.85 ± 0.0494

11.85 ± 0.0588

11.85 ± 0.0609

11.85 ± 0.0784

Explanation / Answer

Ans:

Probability distribution of X is Binomial distribution.

n=15

p=0.9

Mean=np=15*0.9 =13.5

standard deviation=sqrt(np(1-p))=sqrt(13.5*0.1)=1.16