In examining the ability of users to complete a variety of information-seeking tasks on their mobile devices, Nielsen Norman Group assigned sample members to get the answers to a variety of questions like, "How many calories are there typically in a slice of thin-crust pizza?" The success rate for achieving such tasks was 75% for those using touch-screen phones like the iPhone to access the mobile Internet, compared to the 80% for persons accessing websites on a conventional personal computer. Assuming these percentages to be based on independent samples of 500 persons each, and using the 0.01 level of significance, can we conclude that the population success rate with the mobile Internet and touch-screen phone?