A salesperson makes four calls per day. A sample of 100 days gives the following frequenciesof sales volumes.Observed FrequencyNumber of Sales (days)0 301 322 253 104 3Total 100f (x) =n!/x!(n-x)! p^x (1-p)^(n-x)
Records show sales are made to 30% of all sales calls. Assuming independent sales calls,the number of sales per day should follow a binomial distribution. The binomial probabilityfunction presented in Chapter 5 isFor this exercise, assume that the population has a binomial distribution with n 4,p .30, and x 0, 1, 2, 3, and 4.
a. Compute the expected frequencies for x 0, 1, 2, 3, and 4 by using the binomial probability function. Combine categories if necessary to satisfy the requirement that the expected frequency is five or more for all categories.
b. Use the goodness of fit test to determine whether the assumption of a binomial distributionshould be rejected. Use a .05. Because no parameters of the binomial distributionwere estimated from the sample data, the degrees of freedom are k 1 whenk is the number of categories.