To ascertain the effectiveness of their advertising campaigns, firms frequently conduct telephone interviews with consumers.They may use random samples of telephone numbers that are arbitrarily or systematically selected from telephone directories, or they may employ an innovation called random-digit dialing. In this approach, a random number generator mechanically creates the sample of phone numbers to be called. An advantage of randorn-digit dialing is that it can obtain a representative sample from the population of all households with telephones, whereas telephonedirectory sampling obtains a sample only from the population of households with listed telephone numbers.

a. Explain how the random number table (Table I of Appendix B, or a computer) could be used to generate a sample of 7-digit telephone numbers.

b. Use the procedure you described in part a to gcncrate a sample of ten 7-digit telephone numbers

c. Use the procedure you described in part a to generate five 7-digit telephone numbers whose first three digits are 373.