Utility Concerns in Choosing an Assessment Method

Case study must be a minimum of 3-4 pages of original discussion and analysis, not counting the title page, reference page, figures, tables, and appendixes. The statements in each Case Study must be supported by at least 1 scholarly reference, cited throughout the narrative and placed on the reference list in the APA format. 
Randy May is a 32-year-old airplane mechanic for a small airline based in Nantucket Island, Massachusetts. Recently, Randy won $2 million in the New England lottery. Because Randy is relatively young, he decided to invest his winnings in a business to create a future stream of earnings. After weighing many investment decisions, Randy opted to open up a chain of ice cream shops in the Cape Cod area. (As it turns out, Cape Cod and the nearby islands are short of ice cream shops.) Based on his own budgeting, Randy figured he had enough cash to open shops on each of the two islands (Nantucket and Martha’s Vineyard) and two shops in small towns on the Cape (Falmouth and Buzzards Bay). Randy contracted with a local builder and the construction/renovation of the four shops is well under way.
The task that is occupying Randy’s attention now is how to staff the shops. Two weeks ago, he placed advertisements in three area newspapers. So far, he has received 100 applications. Randy has done some informal HR planning and figures he needs to hire 50 employees to staff the four shops. Being a novice at this, Randy is unsure how to select the 50 people he needs to hire. Randy consulted his friend Mary, who owns the lunch counter at the airport. Mary advised Randy that she used the interview to get “the most knowledgeable people possible” and recommended it to Randy because her people had “generally worked out well.” While Randy greatly respected Mary’s advice, on reflection several questions came to mind. Does Mary’s use of the interview mean that it meets Randy’s requirements? How can Randy determine whether his chosen method of selecting employees was effective or ineffective?
Confused, Randy also sought the advice of Professor Ray Higgins, from whom Randy took an HR management course while getting his business degree. After learning of the situation and offering his consulting services, Professor Higgins suggested that Randy choose one of two selection methods (after paying Professor Higgins’s consulting fees, he cannot afford to use both methods). The two methods Professor Higgins recommended are the interview (as Mary recommended) and also a work sample test that entails scooping ice cream and serving it to the customer. Randy estimates that it would cost $100 to interview an applicant and $150 per applicant to administer the work sample. Professor Higgins told Randy that the validity of the interview in predicting overall job performance for customer service employees is r = .30 while the validity of the work sample in predicting overall job performance is r = .50. Professor Higgins also informed Randy that the selection ratio is probably fairly high because there aren’t a lot of job seekers because the minimum wage he plans on paying isn’t likely to attract people in this area. 
Based on the information presented above, Randy would really appreciate it if you could help him answer the following questions:
1. What parts of this information seem most important for the choice of selection measures? How does each piece of information fit with the “choice of assessment method” discussion?
2. If Randy can use only one method, which should he use?
3. If the number of applicants for these jobs increases dramatically (more applications are coming in than Randy expected), how ill your answers to questions 1 and 2 change?
4. What are some additional pieces of information you’d like to have before committing to any of these options? What other criteria might be relevant? 
Please cite references and be very thorough and lengthy.