Question: The University is considering changing the email system that they currently use. Since there are substantial learning costs associated with any new software, the University only wants to change to the new system if it is very confident that there is at least a 20% difference in the proportion of faculty and staff who say they like the new system. In a sample of 140 users of the current system, the University finds that 75 say they like the current system. In another sample of 85 experimental users of the “new” system, the University finds that 72 of them like the new system.

a) Based on both samples, at the 5% level of significance, does it appear that there is at least a 20% difference in the proportion of users who like the two systems?