Consider the following to answer the question(s) below:
The owner of a small convenience store is trying to decide whether to discontinue selling magazines. He suspects that only 5% of the customers buy magazines and thinks that he might be able to sell something more profitable. Before making a final decision, he keeps track of the number of customers who buy magazines each day. On a typical day he has 280 customers in his store.
-On a typical day, what would be the mean number of customers who buy magazines?
A) 280
B) 0
C) 266
D) 14
E) 25

Question

Quizplus · Accepted Answer

Since the owner suspects that only 5% of the customers buy magazines, we can use a binomial distribution to approximate the number of customers who buy magazines in a day. 
The mean of a binomial distribution is given by:
mean = n*p
where n is the number of trials and p is the probability of success in each trial.
In this case, n = 280 (the number of customers) and p = 0.05 (the probability of buying a magazine). 
Thus, the mean number of customers who buy magazines is:
mean = n*p = 280*0.05 = 14. 
Therefore, the answer is D) 14.

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