Dot Miller Owns a Small Chain of Dive Shops

Dot Miller owns a small chain of dive shops.She is interested in knowing how many potential customers she will need to sample in several large cities within a three- to four-hour drive of her shops located on the California coast.She wants to estimate the mean response to a 10-point scale measuring the likelihood that they will subscribe to a dive package which,if they take advantage of all the dives,represents a savings of 50 percent over taking the dives individually.In estimating the standard deviation in the population for the formula for calculating the sample size for estimating a mean,Dot can:

A) rely on the knowledge of other owners in the dive industry to share their knowledge of surveying scuba divers.
B) use some prior knowledge about the population,undertake a pilot study or estimate the range,and divide by 10.
C) use some prior knowledge about the population,undertake a pilot study or estimate the range (7) ,and divide by 6.
D) undertake a pilot study using members of the dive population who live near the present dive shops.
E) None of the above;if you do not have the actual standard deviation,you cannot use the formula.