Question: According to an advertisement, a strain of soybeans planted on soil prepared with a specified fertilizer treatment has a mean yield of 538 bushels per acre and a standard deviation of 96.5 bushels per acre. Twenty farmers who belong to a cooperative plant the soybeans in soil prepared as specified. Each uses a 40-acre plot and records the mean yield per acre. The mean for the sample of 20 farms is 508. Use a .05 level of significance to determine if there is sufficient evidence that the mean yield for the soybeans is different than advertised.