How to test whether the population mean TV "on" time has declined in the past decade.

It has been reported that entertainment behaviours in America are changing and people today are watching less television than in the past (traditional demarcated as programming delivered via broadcast, cable including fibre optic, and satellite). In its place numerous people are surfing the Internet for diversion as well as playing video games as well as watching DVDs.

Let's say in 1998 at least one television was turned on in the average American home 9 hours and 40 minutes per day. Below right is given instance data representing a random sample of households showing the number of minutes in a typical day at least one TV is turned on. Given this data use an suitable statistical test to show whether the population mean TV "on" time has declined in the past decade.