A researcher is interested in whether the certain hour-long film which portrays the insidious effects of the racial prejudice will affect attitudes toward minority group. Two groups of 31 subjects each were randomly chosen and randomly assigned to one of two situations: Group A watched the movie, and Group B spent hour playing cards. Both groups were then given racial-attitude test, wherein high scores represented higher level of prejudice. The data are as follows:
Group A: N= 31; M = 39.62 Group B: N=31; M = 42.60
The estimated standard error of difference between the means was 1.360.
a. Test the null hypothesis at the .05 level.