A survey asked what the most important reason was that people give for not using a wireless phone exclusively. The responses were: (1) Like the safety of traditional phone, (2) Like having a land line for a backup phone, (3) Pricing not attractive enough,

(4) Weak or unreliable cell signal at home, (5) Need phone line for DSL Internet access, and (6) Other. The file titled Wireless contains the responses for 1,088 respondents.

a. Of those respondents 36 or older, determine the probability that an individual in this age group would not use a wireless phone exclusively because of concern about a weak or unreliable cell signal.

b. If three respondents were selected at random from those respondents younger than 36, calculate the probability that at least one of the respondents stated the most important reason for not using a wireless exclusively was that he or she liked having a land line for a backup phone.