What kind of survey (mail, telephone, interview, web, direct observation) would you recommend that a small laundry and dry cleaning business use for each of the following purposes, and why?
a. To estimate the proportion of customers preferring opening hours at 7 a.m. instead of 8 a.m.
b. To estimate the proportion of customers who have only laundry and no dry cleaning.
c. To estimate the proportion of residents in the same zip code who spend more than $20 a month on dry cleaning.
d. To estimate the proportion of its seven employees who think it is too hot inside the building.