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.
Answer: C) Use some prior knowledge about the population, undertake a pilot study or estimate the range (7), and divide by 6.