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Question

In a survey of consumers aged 12 and older, respondents were asked how many cell phones were in use by the household. (No two respondents were from the same household.) Among the respondents, 218 answered "none," 296 said "one," 362 said "two," 148 said "three," and 142 responded with four or more. A survey respondent is selected at random. Find the probability that his/her household has four or more cell phones in use. Is it unlikely for a household to have four or more cell phones in use? Consider an event to be unlikely if its probability is less than or equal to 0.05.

Answer 1

Hi Glorimar,

 

To answer this problem, we must understand how to find the probablity, P, of something.  The probability of an event, E, is found using the following equation:

 

P(E) = E/O_T, 

 

where O_T is the total amount of outcomes.

 

In this case, the total amount of outcomes is equal to the amount of responses in the survey! So O_T = 218 + 296 + 362 + 148 + 142 = 1,166.  

 

E is equal to the number of times our event has happened.  In this case E is the number of times somebody responded with "four or more", 142.

 

So, we can now find that P = 142/1,166 = .122

 

Because .122 > 0.05 we can say that the event is not unlikely.