A small Caribbean island relies heavily on tourist income. There is a need to develop a study so that an estimate can be provided each month as to

a) The number of tourists

b) The length of stay

c) Their activities

d) Their attitudes toward some programs and activities

The plan is to conduct a short interview with each respondent and to leave with them a short questionnaire to be completed and mailed after returning home. Several sampling plans are being considered. One is to generate a random sample of hotel rooms and to interview each occupant. Another involves sampling every nth person that passes a predetermined point in the city. Still another is to sample departing planes and ships. About six plan esandm three ships depart each day. Design a sampling plan so that each month 500 tourists are obtained in the sample.